Move non-gfx things out of `gfx_traits` and create a `base` crate (#32296)

For a long time, `gfx_traits` has held a lot of things unrelated to graphics
and also unrelated to the `gfx` crate (which is mostly about fonts).
This is a cleanup which does a few things:

1. Move non `gfx` crate things out of `gfx_traits`. This is important in
   order to prevent dependency cycles with a different integration between
   layout, script, and fonts.
2. Rename the `msg` crate to `base`. It didn't really contain anything
   to do with messages and instead mostly holds ids, which are used
   across many different crates in Servo. This new crate will hold the
   *rare* data types that are widely used.

Details:

 - All BackgroundHangMonitor-related things from base to a new
   `background_hang_monitor_api` crate.
 - Moved `TraversalDirection` to `script_traits`
 - Moved `Epoch`-related things from `gfx_traits` to `base`.
 - Moved `PrintTree` to base. This should be widely useful in Servo.
 - Moved `WebrenderApi` from `base` to `webrender_traits` and renamed it
   to `WebRenderFontApi`.

163 files changed, 709 insertions, 632 deletions

diff --git a/Cargo.lock b/Cargo.lock
index e909acbbe0e..5fc58b78c20 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -293,20 +293,36 @@ checksum = "0c4b4d0bd25bd0b74681c0ad21497610ce1b7c91b1022cd21c80c6fbdd9476b0"
 name = "background_hang_monitor"
 version = "0.0.1"
 dependencies = [
+ "background_hang_monitor_api",
  "backtrace",
+ "base",
  "crossbeam-channel",
  "ipc-channel",
  "lazy_static",
  "libc",
  "log",
  "mach2",
- "msg",
  "nix 0.27.1",
  "serde_json",
  "unwind-sys",
 ]
 
 [[package]]
+name = "background_hang_monitor_api"
+version = "0.0.1"
+dependencies = [
+ "base",
+ "ipc-channel",
+ "lazy_static",
+ "malloc_size_of",
+ "malloc_size_of_derive",
+ "parking_lot",
+ "serde",
+ "size_of_test",
+ "webrender_api",
+]
+
+[[package]]
 name = "backtrace"
 version = "0.3.71"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -322,6 +338,20 @@ dependencies = [
 ]
 
 [[package]]
+name = "base"
+version = "0.0.1"
+dependencies = [
+ "ipc-channel",
+ "lazy_static",
+ "malloc_size_of",
+ "malloc_size_of_derive",
+ "parking_lot",
+ "serde",
+ "size_of_test",
+ "webrender_api",
+]
+
+[[package]]
 name = "base64"
 version = "0.21.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -821,6 +851,7 @@ dependencies = [
 name = "compositing"
 version = "0.0.1"
 dependencies = [
+ "base",
  "canvas",
  "compositing_traits",
  "crossbeam-channel",
@@ -835,7 +866,6 @@ dependencies = [
  "keyboard-types",
  "libc",
  "log",
- "msg",
  "net_traits",
  "pixels",
  "profile_traits",
@@ -856,6 +886,7 @@ dependencies = [
 name = "compositing_traits"
 version = "0.0.1"
 dependencies = [
+ "base",
  "canvas",
  "crossbeam-channel",
  "embedder_traits",
@@ -864,7 +895,6 @@ dependencies = [
  "ipc-channel",
  "keyboard-types",
  "log",
- "msg",
  "net_traits",
  "script_traits",
  "servo_url",
@@ -886,7 +916,9 @@ name = "constellation"
 version = "0.0.1"
 dependencies = [
  "background_hang_monitor",
+ "background_hang_monitor_api",
  "backtrace",
+ "base",
  "bluetooth_traits",
  "canvas_traits",
  "compositing_traits",
@@ -903,7 +935,6 @@ dependencies = [
  "log",
  "media",
  "metrics",
- "msg",
  "net",
  "net_traits",
  "parking_lot",
@@ -1252,6 +1283,7 @@ dependencies = [
 name = "devtools"
 version = "0.0.1"
 dependencies = [
+ "base",
  "chrono",
  "crossbeam-channel",
  "devtools_traits",
@@ -1260,7 +1292,6 @@ dependencies = [
  "http",
  "ipc-channel",
  "log",
- "msg",
  "serde",
  "serde_json",
  "servo_config",
@@ -1273,12 +1304,12 @@ dependencies = [
 name = "devtools_traits"
 version = "0.0.1"
 dependencies = [
+ "base",
  "bitflags 2.5.0",
  "http",
  "ipc-channel",
  "malloc_size_of",
  "malloc_size_of_derive",
- "msg",
  "serde",
  "servo_url",
  "time 0.1.45",
@@ -1481,13 +1512,13 @@ dependencies = [
 name = "embedder_traits"
 version = "0.0.1"
 dependencies = [
+ "base",
  "cfg-if",
  "crossbeam-channel",
  "ipc-channel",
  "keyboard-types",
  "lazy_static",
  "log",
- "msg",
  "num-derive",
  "num-traits",
  "serde",
@@ -2020,6 +2051,7 @@ dependencies = [
  "unicode-properties",
  "unicode-script",
  "webrender_api",
+ "webrender_traits",
  "xi-unicode",
  "xml-rs",
  "yeslogic-fontconfig-sys",
@@ -3191,6 +3223,7 @@ version = "0.0.1"
 dependencies = [
  "app_units",
  "atomic_refcell",
+ "base",
  "bitflags 2.5.0",
  "canvas_traits",
  "embedder_traits",
@@ -3203,7 +3236,7 @@ dependencies = [
  "lazy_static",
  "log",
  "malloc_size_of",
- "msg",
+ "malloc_size_of_derive",
  "net_traits",
  "parking_lot",
  "profile_traits",
@@ -3234,6 +3267,7 @@ version = "0.0.1"
 dependencies = [
  "app_units",
  "atomic_refcell",
+ "base",
  "bitflags 2.5.0",
  "canvas_traits",
  "cssparser",
@@ -3248,7 +3282,6 @@ dependencies = [
  "ipc-channel",
  "lazy_static",
  "log",
- "msg",
  "net_traits",
  "parking_lot",
  "quickcheck",
@@ -3276,6 +3309,7 @@ name = "layout_thread_2013"
 version = "0.0.1"
 dependencies = [
  "app_units",
+ "base",
  "crossbeam-channel",
  "embedder_traits",
  "euclid",
@@ -3290,7 +3324,6 @@ dependencies = [
  "log",
  "malloc_size_of",
  "metrics",
- "msg",
  "net_traits",
  "parking_lot",
  "profile_traits",
@@ -3316,6 +3349,7 @@ name = "layout_thread_2020"
 version = "0.0.1"
 dependencies = [
  "app_units",
+ "base",
  "crossbeam-channel",
  "embedder_traits",
  "euclid",
@@ -3329,7 +3363,6 @@ dependencies = [
  "log",
  "malloc_size_of",
  "metrics",
- "msg",
  "net_traits",
  "parking_lot",
  "profile_traits",
@@ -3461,6 +3494,7 @@ name = "libservo"
 version = "0.0.1"
 dependencies = [
  "background_hang_monitor",
+ "base",
  "bluetooth",
  "bluetooth_traits",
  "canvas",
@@ -3486,7 +3520,6 @@ dependencies = [
  "log",
  "media",
  "mozangle",
- "msg",
  "net",
  "net_traits",
  "profile",
@@ -3747,12 +3780,12 @@ dependencies = [
 name = "metrics"
 version = "0.0.1"
 dependencies = [
+ "base",
  "gfx_traits",
  "ipc-channel",
  "log",
  "malloc_size_of",
  "malloc_size_of_derive",
- "msg",
  "profile_traits",
  "script_traits",
  "servo_config",
@@ -3763,10 +3796,10 @@ dependencies = [
 name = "metrics_tests"
 version = "0.0.1"
 dependencies = [
+ "base",
  "gfx_traits",
  "ipc-channel",
  "metrics",
- "msg",
  "profile_traits",
  "servo_url",
  "time 0.1.45",
@@ -3880,20 +3913,6 @@ dependencies = [
 ]
 
 [[package]]
-name = "msg"
-version = "0.0.1"
-dependencies = [
- "ipc-channel",
- "lazy_static",
- "malloc_size_of",
- "malloc_size_of_derive",
- "parking_lot",
- "serde",
- "size_of_test",
- "webrender_api",
-]
-
-[[package]]
 name = "muldiv"
 version = "1.0.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -3956,6 +3975,7 @@ version = "0.0.1"
 dependencies = [
  "async-recursion",
  "async-tungstenite",
+ "base",
  "base64",
  "brotli",
  "bytes",
@@ -3982,7 +4002,6 @@ dependencies = [
  "malloc_size_of_derive",
  "mime",
  "mime_guess",
- "msg",
  "net_traits",
  "percent-encoding",
  "pixels",
@@ -4013,6 +4032,7 @@ dependencies = [
 name = "net_traits"
 version = "0.0.1"
 dependencies = [
+ "base",
  "content-security-policy",
  "cookie 0.12.0",
  "embedder_traits",
@@ -4027,7 +4047,6 @@ dependencies = [
  "malloc_size_of",
  "malloc_size_of_derive",
  "mime",
- "msg",
  "num-traits",
  "percent-encoding",
  "pixels",
@@ -5015,7 +5034,9 @@ dependencies = [
  "app_units",
  "arrayvec",
  "atomic_refcell",
+ "background_hang_monitor_api",
  "backtrace",
+ "base",
  "base64",
  "bitflags 2.5.0",
  "bluetooth_traits",
@@ -5059,7 +5080,6 @@ dependencies = [
  "mime_guess",
  "mozangle",
  "mozjs",
- "msg",
  "net_traits",
  "num-traits",
  "num_cpus",
@@ -5113,6 +5133,7 @@ version = "0.0.1"
 dependencies = [
  "app_units",
  "atomic_refcell",
+ "base",
  "canvas_traits",
  "crossbeam-channel",
  "euclid",
@@ -5124,12 +5145,12 @@ dependencies = [
  "malloc_size_of",
  "malloc_size_of_derive",
  "metrics",
- "msg",
  "net_traits",
  "profile_traits",
  "range",
  "script_traits",
  "selectors",
+ "serde",
  "servo_arc",
  "servo_atoms",
  "servo_url",
@@ -5152,6 +5173,8 @@ dependencies = [
 name = "script_traits"
 version = "0.0.1"
 dependencies = [
+ "background_hang_monitor_api",
+ "base",
  "bitflags 2.5.0",
  "bluetooth_traits",
  "canvas_traits",
@@ -5170,7 +5193,6 @@ dependencies = [
  "malloc_size_of",
  "malloc_size_of_derive",
  "media",
- "msg",
  "net_traits",
  "pixels",
  "profile_traits",
@@ -7048,6 +7070,7 @@ dependencies = [
 name = "webdriver_server"
 version = "0.0.1"
 dependencies = [
+ "base",
  "base64",
  "compositing_traits",
  "cookie 0.12.0",
@@ -7058,7 +7081,6 @@ dependencies = [
  "ipc-channel",
  "keyboard-types",
  "log",
- "msg",
  "net_traits",
  "pixels",
  "script_traits",
@@ -7076,11 +7098,11 @@ name = "webgpu"
 version = "0.0.1"
 dependencies = [
  "arrayvec",
+ "base",
  "euclid",
  "ipc-channel",
  "log",
  "malloc_size_of",
- "msg",
  "serde",
  "servo_config",
  "smallvec",
diff --git a/Cargo.toml b/Cargo.toml
index 0ea83dc0b7a..17e01a50b41 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -15,7 +15,9 @@ app_units = "0.7"
 arrayvec = "0.7"
 async-tungstenite = { version = "0.23", features = ["tokio-rustls-webpki-roots"] }
 atomic_refcell = "0.1.13"
+background_hang_monitor_api = { path = "components/shared/background_hang_monitor" }
 backtrace = "0.3"
+base = { path = "components/shared/base" }
 base64 = "0.21.7"
 bitflags = "2.5"
 bluetooth_traits = { path = "components/shared/bluetooth" }
@@ -68,7 +70,6 @@ malloc_size_of_derive = "0.1"
 mime = "0.3.13"
 mime_guess = "2.0.3"
 mozangle = "0.5.1"
-msg = { path = "components/shared/msg" }
 net_traits = { path = "components/shared/net" }
 num-traits = "0.2"
 num_cpus = "1.1.0"
diff --git a/components/background_hang_monitor/Cargo.toml b/components/background_hang_monitor/Cargo.toml
index 2e0a4630c98..d126fd3059a 100644
--- a/components/background_hang_monitor/Cargo.toml
+++ b/components/background_hang_monitor/Cargo.toml
@@ -13,12 +13,13 @@ test = false
 doctest = false
 
 [dependencies]
+background_hang_monitor_api = { workspace = true }
 backtrace = { workspace = true }
+base = { workspace = true }
 crossbeam-channel = { workspace = true }
 ipc-channel = { workspace = true }
 libc = { workspace = true }
 log = { workspace = true }
-msg = { workspace = true }
 serde_json = { workspace = true }
 
 [dev-dependencies]
diff --git a/components/background_hang_monitor/background_hang_monitor.rs b/components/background_hang_monitor/background_hang_monitor.rs
index e57cf4b4f11..c0f0d22af14 100644
--- a/components/background_hang_monitor/background_hang_monitor.rs
+++ b/components/background_hang_monitor/background_hang_monitor.rs
@@ -8,15 +8,15 @@ use std::sync::{Arc, Weak};
 use std::thread;
 use std::time::{Duration, Instant};
 
-use crossbeam_channel::{after, never, select, unbounded, Receiver, Sender};
-use ipc_channel::ipc::{IpcReceiver, IpcSender};
-use ipc_channel::router::ROUTER;
-use log::warn;
-use msg::constellation_msg::{
+use background_hang_monitor_api::{
     BackgroundHangMonitor, BackgroundHangMonitorClone, BackgroundHangMonitorControlMsg,
     BackgroundHangMonitorExitSignal, BackgroundHangMonitorRegister, HangAlert, HangAnnotation,
     HangMonitorAlert, MonitoredComponentId,
 };
+use crossbeam_channel::{after, never, select, unbounded, Receiver, Sender};
+use ipc_channel::ipc::{IpcReceiver, IpcSender};
+use ipc_channel::router::ROUTER;
+use log::warn;
 
 use crate::sampler::{NativeStack, Sampler};
 
diff --git a/components/background_hang_monitor/sampler.rs b/components/background_hang_monitor/sampler.rs
index 82f6b7e0fde..9c67908c463 100644
--- a/components/background_hang_monitor/sampler.rs
+++ b/components/background_hang_monitor/sampler.rs
@@ -4,7 +4,7 @@
 
 use std::ptr;
 
-use msg::constellation_msg::{HangProfile, HangProfileSymbol};
+use background_hang_monitor_api::{HangProfile, HangProfileSymbol};
 
 const MAX_NATIVE_FRAMES: usize = 1024;
 
diff --git a/components/background_hang_monitor/tests/hang_monitor_tests.rs b/components/background_hang_monitor/tests/hang_monitor_tests.rs
index f98978fea02..36a6b45eec3 100644
--- a/components/background_hang_monitor/tests/hang_monitor_tests.rs
+++ b/components/background_hang_monitor/tests/hang_monitor_tests.rs
@@ -10,12 +10,12 @@ use std::thread;
 use std::time::Duration;
 
 use background_hang_monitor::HangMonitorRegister;
-use ipc_channel::ipc;
-use msg::constellation_msg::{
+use background_hang_monitor_api::{
     BackgroundHangMonitorControlMsg, BackgroundHangMonitorExitSignal, HangAlert, HangAnnotation,
     HangMonitorAlert, MonitoredComponentId, MonitoredComponentType, ScriptHangAnnotation,
-    TEST_PIPELINE_ID,
 };
+use base::id::TEST_PIPELINE_ID;
+use ipc_channel::ipc;
 
 lazy_static::lazy_static! {
     static ref SERIAL: Mutex<()> = Mutex::new(());
diff --git a/components/compositing/Cargo.toml b/components/compositing/Cargo.toml
index e1c0f0c7042..37c1b6b6a21 100644
--- a/components/compositing/Cargo.toml
+++ b/components/compositing/Cargo.toml
@@ -16,6 +16,7 @@ default = []
 multiview = []
 
 [dependencies]
+base = { workspace = true }
 canvas = { path = "../canvas" }
 compositing_traits = { workspace = true }
 crossbeam-channel = { workspace = true }
@@ -30,7 +31,6 @@ ipc-channel = { workspace = true }
 keyboard-types = { workspace = true }
 libc = { workspace = true }
 log = { workspace = true }
-msg = { workspace = true }
 net_traits = { workspace = true }
 pixels = { path = "../pixels" }
 profile_traits = { workspace = true }
diff --git a/components/compositing/compositor.rs b/components/compositing/compositor.rs
index 9e55648f5eb..d211a4c4783 100644
--- a/components/compositing/compositor.rs
+++ b/components/compositing/compositor.rs
@@ -11,6 +11,8 @@ use std::iter::once;
 use std::rc::Rc;
 use std::time::{Duration, Instant, SystemTime, UNIX_EPOCH};
 
+use base::id::{PipelineId, TopLevelBrowsingContextId, WebViewId};
+use base::{Epoch, WebRenderEpochToU16};
 use canvas::canvas_paint_thread::ImageUpdate;
 use compositing_traits::{
     CanvasToCompositorMsg, CompositionPipeline, CompositorMsg, CompositorReceiver,
@@ -21,12 +23,10 @@ use embedder_traits::Cursor;
 use euclid::{Point2D, Rect, Scale, Transform3D, Vector2D};
 use fnv::{FnvHashMap, FnvHashSet};
 use gfx::rendering_context::RenderingContext;
-use gfx_traits::{Epoch, WebRenderEpochToU16};
 use image::{DynamicImage, ImageFormat};
 use ipc_channel::ipc;
 use libc::c_void;
 use log::{debug, error, info, trace, warn};
-use msg::constellation_msg::{PipelineId, TopLevelBrowsingContextId, WebViewId};
 use net_traits::image::base::Image;
 use net_traits::image_cache::CorsStatus;
 use pixels::PixelFormat;
diff --git a/components/compositing/webview.rs b/components/compositing/webview.rs
index b8698381520..1263f877012 100644
--- a/components/compositing/webview.rs
+++ b/components/compositing/webview.rs
@@ -4,7 +4,7 @@
 
 use std::collections::HashMap;
 
-use msg::constellation_msg::{PipelineId, WebViewId};
+use base::id::{PipelineId, WebViewId};
 use webrender_api::units::DeviceRect;
 
 #[derive(Debug, Default)]
@@ -113,7 +113,7 @@ impl<WebView> WebViewManager<WebView> {
 mod test {
     use std::num::NonZeroU32;
 
-    use msg::constellation_msg::{
+    use base::id::{
         BrowsingContextId, BrowsingContextIndex, PipelineNamespace, PipelineNamespaceId,
         TopLevelBrowsingContextId,
     };
diff --git a/components/compositing/windowing.rs b/components/compositing/windowing.rs
index fc7ef379be1..bb11457aa47 100644
--- a/components/compositing/windowing.rs
+++ b/components/compositing/windowing.rs
@@ -7,14 +7,15 @@
 use std::fmt::{Debug, Error, Formatter};
 use std::time::Duration;
 
+use base::id::{PipelineId, TopLevelBrowsingContextId};
 use embedder_traits::{EmbedderProxy, EventLoopWaker};
 use euclid::Scale;
 use gfx::rendering_context::RenderingContext;
 use keyboard_types::KeyboardEvent;
 use libc::c_void;
-use msg::constellation_msg::{PipelineId, TopLevelBrowsingContextId, TraversalDirection};
 use script_traits::{
-    GamepadEvent, MediaSessionActionType, MouseButton, TouchEventType, TouchId, WheelDelta,
+    GamepadEvent, MediaSessionActionType, MouseButton, TouchEventType, TouchId, TraversalDirection,
+    WheelDelta,
 };
 use servo_geometry::DeviceIndependentPixel;
 use servo_url::ServoUrl;
diff --git a/components/constellation/Cargo.toml b/components/constellation/Cargo.toml
index 0f10a5a23fb..851d207dfc2 100644
--- a/components/constellation/Cargo.toml
+++ b/components/constellation/Cargo.toml
@@ -15,8 +15,10 @@ default = []
 multiview = []
 
 [dependencies]
+background_hang_monitor_api = { workspace = true }
 background_hang_monitor = { path = "../background_hang_monitor" }
 backtrace = { workspace = true }
+base = { workspace = true }
 bluetooth_traits = { workspace = true }
 canvas_traits = { workspace = true }
 compositing_traits = { workspace = true }
@@ -32,7 +34,6 @@ keyboard-types = { workspace = true }
 log = { workspace = true }
 media = { path = "../media" }
 metrics = { path = "../metrics" }
-msg = { workspace = true }
 net = { path = "../net" }
 net_traits = { workspace = true }
 parking_lot = { workspace = true }
diff --git a/components/constellation/browsingcontext.rs b/components/constellation/browsingcontext.rs
index dbb956ad6c5..4f55c0fe3ac 100644
--- a/components/constellation/browsingcontext.rs
+++ b/components/constellation/browsingcontext.rs
@@ -4,11 +4,9 @@
 
 use std::collections::{HashMap, HashSet};
 
+use base::id::{BrowsingContextGroupId, BrowsingContextId, PipelineId, TopLevelBrowsingContextId};
 use euclid::Size2D;
 use log::warn;
-use msg::constellation_msg::{
-    BrowsingContextGroupId, BrowsingContextId, PipelineId, TopLevelBrowsingContextId,
-};
 use style_traits::CSSPixel;
 
 use crate::pipeline::Pipeline;
diff --git a/components/constellation/constellation.rs b/components/constellation/constellation.rs
index 53b0ae8d412..14176fc0739 100644
--- a/components/constellation/constellation.rs
+++ b/components/constellation/constellation.rs
@@ -94,6 +94,15 @@ use std::sync::{Arc, Mutex};
 use std::{process, thread};
 
 use background_hang_monitor::HangMonitorRegister;
+use background_hang_monitor_api::{
+    BackgroundHangMonitorControlMsg, BackgroundHangMonitorRegister, HangMonitorAlert,
+};
+use base::id::{
+    BroadcastChannelRouterId, BrowsingContextGroupId, BrowsingContextId, HistoryStateId,
+    MessagePortId, MessagePortRouterId, PipelineId, PipelineNamespace, PipelineNamespaceId,
+    PipelineNamespaceRequest, TopLevelBrowsingContextId, WebViewId,
+};
+use base::Epoch;
 use bluetooth_traits::BluetoothRequest;
 use canvas_traits::canvas::{CanvasId, CanvasMsg};
 use canvas_traits::webgl::WebGLThreads;
@@ -113,7 +122,6 @@ use embedder_traits::{
 use euclid::default::Size2D as UntypedSize2D;
 use euclid::Size2D;
 use gfx::font_cache_thread::FontCacheThread;
-use gfx_traits::Epoch;
 use ipc_channel::ipc::{self, IpcReceiver, IpcSender};
 use ipc_channel::router::ROUTER;
 use ipc_channel::Error as IpcError;
@@ -121,12 +129,6 @@ use keyboard_types::webdriver::Event as WebDriverInputEvent;
 use keyboard_types::KeyboardEvent;
 use log::{debug, error, info, trace, warn};
 use media::{GLPlayerThreads, WindowGLContext};
-use msg::constellation_msg::{
-    BackgroundHangMonitorControlMsg, BackgroundHangMonitorRegister, BroadcastChannelRouterId,
-    BrowsingContextGroupId, BrowsingContextId, HangMonitorAlert, HistoryStateId, MessagePortId,
-    MessagePortRouterId, PipelineId, PipelineNamespace, PipelineNamespaceId,
-    PipelineNamespaceRequest, TopLevelBrowsingContextId, TraversalDirection, WebViewId,
-};
 use net_traits::pub_domains::reg_host;
 use net_traits::request::{Referrer, RequestBuilder};
 use net_traits::storage_thread::{StorageThreadMsg, StorageType};
@@ -142,8 +144,8 @@ use script_traits::{
     LoadData, LoadOrigin, LogEntry, MediaSessionActionType, MessagePortMsg, MouseEventType,
     PortMessageTask, SWManagerMsg, SWManagerSenders, ScriptMsg as FromScriptMsg,
     ScriptToConstellationChan, ServiceWorkerManagerFactory, ServiceWorkerMsg,
-    StructuredSerializedData, TimerSchedulerMsg, UpdatePipelineIdReason, WebDriverCommandMsg,
-    WindowSizeData, WindowSizeType,
+    StructuredSerializedData, TimerSchedulerMsg, TraversalDirection, UpdatePipelineIdReason,
+    WebDriverCommandMsg, WindowSizeData, WindowSizeType,
 };
 use serde::{Deserialize, Serialize};
 use servo_config::{opts, pref};
diff --git a/components/constellation/logging.rs b/components/constellation/logging.rs
index 672b63d1557..f2ca53d1f44 100644
--- a/components/constellation/logging.rs
+++ b/components/constellation/logging.rs
@@ -7,10 +7,10 @@ use std::sync::Arc;
 use std::thread;
 
 use backtrace::Backtrace;
+use base::id::TopLevelBrowsingContextId;
 use compositing_traits::ConstellationMsg as FromCompositorMsg;
 use crossbeam_channel::Sender;
 use log::{Level, LevelFilter, Log, Metadata, Record};
-use msg::constellation_msg::TopLevelBrowsingContextId;
 use parking_lot::ReentrantMutex;
 use script_traits::{LogEntry, ScriptMsg as FromScriptMsg, ScriptToConstellationChan};
 
diff --git a/components/constellation/network_listener.rs b/components/constellation/network_listener.rs
index a3dd8c11027..9ff19b32648 100644
--- a/components/constellation/network_listener.rs
+++ b/components/constellation/network_listener.rs
@@ -6,12 +6,12 @@
 //! Any redirects that are encountered are followed. Whenever a non-redirect
 //! response is received, it is forwarded to the appropriate script thread.
 
+use base::id::PipelineId;
 use crossbeam_channel::Sender;
 use http::HeaderMap;
 use ipc_channel::ipc;
 use ipc_channel::router::ROUTER;
 use log::warn;
-use msg::constellation_msg::PipelineId;
 use net::http_loader::{set_default_accept, set_default_accept_language};
 use net_traits::request::{Destination, Referrer, RequestBuilder};
 use net_traits::response::ResponseInit;
diff --git a/components/constellation/pipeline.rs b/components/constellation/pipeline.rs
index 551c41929ca..000a52768ac 100644
--- a/components/constellation/pipeline.rs
+++ b/components/constellation/pipeline.rs
@@ -8,6 +8,14 @@ use std::rc::Rc;
 use std::sync::Arc;
 
 use background_hang_monitor::HangMonitorRegister;
+use background_hang_monitor_api::{
+    BackgroundHangMonitorControlMsg, BackgroundHangMonitorRegister, HangMonitorAlert,
+};
+use base::id::{
+    BrowsingContextId, HistoryStateId, PipelineId, PipelineNamespace, PipelineNamespaceId,
+    PipelineNamespaceRequest, TopLevelBrowsingContextId,
+};
+use base::Epoch;
 use bluetooth_traits::BluetoothRequest;
 use canvas_traits::webgl::WebGLPipeline;
 use compositing_traits::{CompositionPipeline, CompositorMsg, CompositorProxy};
@@ -15,17 +23,11 @@ use crossbeam_channel::{unbounded, Sender};
 use devtools_traits::{DevtoolsControlMsg, ScriptToDevtoolsControlMsg};
 use embedder_traits::EventLoopWaker;
 use gfx::font_cache_thread::FontCacheThread;
-use gfx_traits::Epoch;
 use ipc_channel::ipc::{self, IpcReceiver, IpcSender};
 use ipc_channel::router::ROUTER;
 use ipc_channel::Error;
 use log::{debug, error, warn};
 use media::WindowGLContext;
-use msg::constellation_msg::{
-    BackgroundHangMonitorControlMsg, BackgroundHangMonitorRegister, BrowsingContextId,
-    HangMonitorAlert, HistoryStateId, PipelineId, PipelineNamespace, PipelineNamespaceId,
-    PipelineNamespaceRequest, TopLevelBrowsingContextId,
-};
 use net::image_cache::ImageCacheImpl;
 use net_traits::image_cache::ImageCache;
 use net_traits::ResourceThreads;
diff --git a/components/constellation/session_history.rs b/components/constellation/session_history.rs
index 9e6f765ee15..7bd4ef2c288 100644
--- a/components/constellation/session_history.rs
+++ b/components/constellation/session_history.rs
@@ -5,11 +5,9 @@
 use std::cmp::PartialEq;
 use std::fmt;
 
+use base::id::{BrowsingContextId, HistoryStateId, PipelineId, TopLevelBrowsingContextId};
 use euclid::Size2D;
 use log::debug;
-use msg::constellation_msg::{
-    BrowsingContextId, HistoryStateId, PipelineId, TopLevelBrowsingContextId,
-};
 use script_traits::LoadData;
 use servo_url::ServoUrl;
 use style_traits::CSSPixel;
diff --git a/components/constellation/webview.rs b/components/constellation/webview.rs
index ddd51e31848..31d7937f9e2 100644
--- a/components/constellation/webview.rs
+++ b/components/constellation/webview.rs
@@ -4,7 +4,7 @@
 
 use std::collections::HashMap;
 
-use msg::constellation_msg::TopLevelBrowsingContextId;
+use base::id::TopLevelBrowsingContextId;
 
 #[derive(Debug)]
 pub struct WebViewManager<WebView> {
@@ -99,7 +99,7 @@ impl<WebView> WebViewManager<WebView> {
 mod test {
     use std::num::NonZeroU32;
 
-    use msg::constellation_msg::{
+    use base::id::{
         BrowsingContextId, BrowsingContextIndex, PipelineNamespace, PipelineNamespaceId,
         TopLevelBrowsingContextId, WebViewId,
     };
diff --git a/components/devtools/Cargo.toml b/components/devtools/Cargo.toml
index 12dc883e59f..20aaced297f 100644
--- a/components/devtools/Cargo.toml
+++ b/components/devtools/Cargo.toml
@@ -14,6 +14,7 @@ path = "lib.rs"
 chrono = "0.4"
 
 [dependencies]
+base = { workspace = true }
 chrono = "0.4"
 crossbeam-channel = { workspace = true }
 devtools_traits = { workspace = true }
@@ -22,7 +23,6 @@ headers = { workspace = true }
 http = { workspace = true }
 ipc-channel = { workspace = true }
 log = { workspace = true }
-msg = { workspace = true }
 serde = { workspace = true }
 serde_json = { workspace = true }
 servo_config = { path = "../config" }
diff --git a/components/devtools/actors/browsing_context.rs b/components/devtools/actors/browsing_context.rs
index af67814d127..0f0dd5a8b1e 100644
--- a/components/devtools/actors/browsing_context.rs
+++ b/components/devtools/actors/browsing_context.rs
@@ -10,10 +10,10 @@ use std::cell::{Cell, RefCell};
 use std::collections::HashMap;
 use std::net::TcpStream;
 
+use base::id::{BrowsingContextId, PipelineId};
 use devtools_traits::DevtoolScriptControlMsg::{self, WantsLiveNotifications};
 use devtools_traits::{DevtoolsPageInfo, NavigationState};
 use ipc_channel::ipc::IpcSender;
-use msg::constellation_msg::{BrowsingContextId, PipelineId};
 use serde::Serialize;
 use serde_json::{Map, Value};
 
diff --git a/components/devtools/actors/console.rs b/components/devtools/actors/console.rs
index b60e506ba43..2587a501bc8 100644
--- a/components/devtools/actors/console.rs
+++ b/components/devtools/actors/console.rs
@@ -11,6 +11,7 @@ use std::collections::HashMap;
 use std::net::TcpStream;
 use std::time::{SystemTime, UNIX_EPOCH};
 
+use base::id::TEST_PIPELINE_ID;
 use devtools_traits::EvaluateJSReply::{
     ActorValue, BooleanValue, NullValue, NumberValue, StringValue, VoidValue,
 };
@@ -20,7 +21,6 @@ use devtools_traits::{
 };
 use ipc_channel::ipc::{self, IpcSender};
 use log::debug;
-use msg::constellation_msg::TEST_PIPELINE_ID;
 use serde::Serialize;
 use serde_json::{self, Map, Number, Value};
 use uuid::Uuid;
diff --git a/components/devtools/actors/framerate.rs b/components/devtools/actors/framerate.rs
index 5428a5cba67..6a1adaca016 100644
--- a/components/devtools/actors/framerate.rs
+++ b/components/devtools/actors/framerate.rs
@@ -5,9 +5,9 @@
 use std::mem;
 use std::net::TcpStream;
 
+use base::id::PipelineId;
 use devtools_traits::DevtoolScriptControlMsg;
 use ipc_channel::ipc::IpcSender;
-use msg::constellation_msg::PipelineId;
 use serde_json::{Map, Value};
 
 use crate::actor::{Actor, ActorMessageStatus, ActorRegistry};
diff --git a/components/devtools/actors/inspector.rs b/components/devtools/actors/inspector.rs
index eae82683748..586d5c01c63 100644
--- a/components/devtools/actors/inspector.rs
+++ b/components/devtools/actors/inspector.rs
@@ -7,12 +7,12 @@
 use std::cell::RefCell;
 use std::net::TcpStream;
 
+use base::id::PipelineId;
 use devtools_traits::DevtoolScriptControlMsg::{
     GetChildren, GetDocumentElement, GetLayout, GetRootNode, ModifyAttribute,
 };
 use devtools_traits::{ComputedNodeLayout, DevtoolScriptControlMsg, NodeInfo};
 use ipc_channel::ipc::{self, IpcSender};
-use msg::constellation_msg::PipelineId;
 use serde::Serialize;
 use serde_json::{self, Map, Value};
 
diff --git a/components/devtools/actors/timeline.rs b/components/devtools/actors/timeline.rs
index 7931f083426..c54f55ee443 100644
--- a/components/devtools/actors/timeline.rs
+++ b/components/devtools/actors/timeline.rs
@@ -9,10 +9,10 @@ use std::sync::{Arc, Mutex};
 use std::thread;
 use std::time::Duration;
 
+use base::id::PipelineId;
 use devtools_traits::DevtoolScriptControlMsg::{DropTimelineMarkers, SetTimelineMarkers};
 use devtools_traits::{DevtoolScriptControlMsg, PreciseTime, TimelineMarker, TimelineMarkerType};
 use ipc_channel::ipc::{self, IpcReceiver, IpcSender};
-use msg::constellation_msg::PipelineId;
 use serde::{Serialize, Serializer};
 use serde_json::{Map, Value};
 
diff --git a/components/devtools/actors/worker.rs b/components/devtools/actors/worker.rs
index 3daab6d74a1..0c7bbb24ff5 100644
--- a/components/devtools/actors/worker.rs
+++ b/components/devtools/actors/worker.rs
@@ -6,10 +6,10 @@ use std::cell::RefCell;
 use std::collections::HashMap;
 use std::net::TcpStream;
 
+use base::id::TEST_PIPELINE_ID;
 use devtools_traits::DevtoolScriptControlMsg::WantsLiveNotifications;
 use devtools_traits::{DevtoolScriptControlMsg, WorkerId};
 use ipc_channel::ipc::IpcSender;
-use msg::constellation_msg::TEST_PIPELINE_ID;
 use serde::Serialize;
 use serde_json::{Map, Value};
 use servo_url::ServoUrl;
diff --git a/components/devtools/lib.rs b/components/devtools/lib.rs
index 30e37f10fd4..1dbc4cd1b76 100644
--- a/components/devtools/lib.rs
+++ b/components/devtools/lib.rs
@@ -20,6 +20,7 @@ use std::net::{Shutdown, TcpListener, TcpStream};
 use std::sync::{Arc, Mutex};
 use std::thread;
 
+use base::id::{BrowsingContextId, PipelineId};
 use crossbeam_channel::{unbounded, Receiver, Sender};
 use devtools_traits::{
     ChromeToDevtoolsControlMsg, ConsoleMessage, DevtoolScriptControlMsg, DevtoolsControlMsg,
@@ -29,7 +30,6 @@ use devtools_traits::{
 use embedder_traits::{EmbedderMsg, EmbedderProxy, PromptDefinition, PromptOrigin, PromptResult};
 use ipc_channel::ipc::{self, IpcSender};
 use log::{debug, warn};
-use msg::constellation_msg::{BrowsingContextId, PipelineId};
 use serde::Serialize;
 use servo_rand::RngCore;
 
diff --git a/components/gfx/Cargo.toml b/components/gfx/Cargo.toml
index dd4ad758a6e..e9871643431 100644
--- a/components/gfx/Cargo.toml
+++ b/components/gfx/Cargo.toml
@@ -44,6 +44,7 @@ unicode-bidi = { workspace = true, features = ["with_serde"] }
 unicode-properties = { workspace = true }
 unicode-script = { workspace = true }
 webrender_api = { workspace = true }
+webrender_traits = { workspace = true }
 xi-unicode = { workspace = true }
 
 [target.'cfg(target_os = "macos")'.dependencies]
diff --git a/components/gfx/font_cache_thread.rs b/components/gfx/font_cache_thread.rs
index aea32225e24..12f72ab309d 100644
--- a/components/gfx/font_cache_thread.rs
+++ b/components/gfx/font_cache_thread.rs
@@ -10,7 +10,6 @@ use std::{f32, fmt, mem, thread};
 
 use app_units::Au;
 use atomic_refcell::AtomicRefCell;
-use gfx_traits::WebrenderApi;
 use ipc_channel::ipc::{self, IpcBytesSender, IpcReceiver, IpcSender};
 use log::{debug, trace};
 use malloc_size_of_derive::MallocSizeOf;
@@ -30,6 +29,7 @@ use style::values::computed::font::{FixedPoint, FontStyleFixedPoint};
 use style::values::computed::{FontStretch, FontWeight};
 use style::values::specified::FontStretch as SpecifiedFontStretch;
 use webrender_api::{FontInstanceFlags, FontInstanceKey, FontKey};
+use webrender_traits::WebRenderFontApi;
 
 use crate::font::{FontDescriptor, FontFamilyDescriptor, FontFamilyName, FontSearchScope};
 use crate::font_context::FontSource;
@@ -160,7 +160,7 @@ struct FontCache {
     local_families: HashMap<LowercaseString, FontTemplates>,
     web_families: HashMap<LowercaseString, FontTemplates>,
     core_resource_thread: CoreResourceThread,
-    webrender_api: Box<dyn WebrenderApi>,
+    webrender_api: Box<dyn WebRenderFontApi>,
     webrender_fonts: HashMap<FontIdentifier, FontKey>,
     font_instances: HashMap<(FontKey, Au), FontInstanceKey>,
 }
@@ -577,7 +577,7 @@ impl From<&FontFaceRuleData> for CSSFontFaceDescriptors {
 impl FontCacheThread {
     pub fn new(
         core_resource_thread: CoreResourceThread,
-        webrender_api: Box<dyn WebrenderApi + Send>,
+        webrender_api: Box<dyn WebRenderFontApi + Send>,
     ) -> FontCacheThread {
         let (chan, port) = ipc::channel().unwrap();
 
diff --git a/components/layout/Cargo.toml b/components/layout/Cargo.toml
index 6df0d11c36f..f63002b5fe3 100644
--- a/components/layout/Cargo.toml
+++ b/components/layout/Cargo.toml
@@ -15,6 +15,7 @@ doctest = false
 [dependencies]
 app_units = { workspace = true }
 atomic_refcell = { workspace = true }
+base = { workspace = true }
 bitflags = { workspace = true }
 canvas_traits = { workspace = true }
 embedder_traits = { workspace = true }
@@ -27,7 +28,7 @@ ipc-channel = { workspace = true }
 lazy_static = { workspace = true }
 log = { workspace = true }
 malloc_size_of = { workspace = true }
-msg = { workspace = true }
+malloc_size_of_derive = { workspace = true }
 net_traits = { workspace = true }
 parking_lot = { workspace = true }
 profile_traits = { workspace = true }
diff --git a/components/layout/block.rs b/components/layout/block.rs
index 1aa32668e89..4ecdc44d2d1 100644
--- a/components/layout/block.rs
+++ b/components/layout/block.rs
@@ -30,9 +30,9 @@ use std::fmt;
 use std::sync::Arc;
 
 use app_units::{Au, MAX_AU};
+use base::print_tree::PrintTree;
 use bitflags::bitflags;
 use euclid::default::{Point2D, Rect, SideOffsets2D, Size2D};
-use gfx_traits::print_tree::PrintTree;
 use log::{debug, trace};
 use serde::{Serialize, Serializer};
 use servo_geometry::MaxRect;
diff --git a/components/layout/context.rs b/components/layout/context.rs
index 5cedf5d38aa..5767717e371 100644
--- a/components/layout/context.rs
+++ b/components/layout/context.rs
@@ -9,10 +9,10 @@ use std::hash::BuildHasherDefault;
 use std::sync::{Arc, Mutex};
 use std::thread;
 
+use base::id::PipelineId;
 use fnv::FnvHasher;
 use gfx::font_cache_thread::FontCacheThread;
 use gfx::font_context::FontContext;
-use msg::constellation_msg::PipelineId;
 use net_traits::image_cache::{
     ImageCache, ImageCacheResult, ImageOrMetadataAvailable, UsePlaceholder,
 };
diff --git a/components/layout/display_list/builder.rs b/components/layout/display_list/builder.rs
index 335a5a66823..0fba6875d2f 100644
--- a/components/layout/display_list/builder.rs
+++ b/components/layout/display_list/builder.rs
@@ -13,6 +13,7 @@ use std::sync::Arc;
 use std::{f32, mem};
 
 use app_units::{Au, AU_PER_PX};
+use base::id::{BrowsingContextId, PipelineId};
 use bitflags::bitflags;
 use canvas_traits::canvas::{CanvasMsg, FromLayoutMsg};
 use embedder_traits::Cursor;
@@ -21,12 +22,11 @@ use euclid::{rect, SideOffsets2D};
 use fnv::FnvHashMap;
 use gfx::text::glyph::ByteIndex;
 use gfx::text::TextRun;
-use gfx_traits::{combine_id_with_fragment_type, FragmentType, StackingContextId};
 use ipc_channel::ipc;
 use log::{debug, warn};
-use msg::constellation_msg::{BrowsingContextId, PipelineId};
 use net_traits::image_cache::UsePlaceholder;
 use range::Range;
+use script_layout_interface::{combine_id_with_fragment_type, FragmentType};
 use script_traits::compositor::ScrollSensitivity;
 use servo_config::opts;
 use servo_geometry::{self, MaxRect};
@@ -53,6 +53,7 @@ use webrender_api::{
     NinePatchBorderSource, NormalBorder, PropertyBinding, StickyOffsetBounds,
 };
 
+use super::StackingContextId;
 use crate::block::BlockFlow;
 use crate::context::LayoutContext;
 use crate::display_list::background::{self, get_cyclic};
diff --git a/components/layout/display_list/items.rs b/components/layout/display_list/items.rs
index 193a9f6c461..6fe14f03143 100644
--- a/components/layout/display_list/items.rs
+++ b/components/layout/display_list/items.rs
@@ -16,11 +16,10 @@ use std::cmp::Ordering;
 use std::collections::HashMap;
 use std::{f32, fmt};
 
+use base::id::PipelineId;
+use base::print_tree::PrintTree;
 use embedder_traits::Cursor;
 use euclid::{SideOffsets2D, Vector2D};
-use gfx_traits::print_tree::PrintTree;
-use gfx_traits::{self, StackingContextId};
-use msg::constellation_msg::PipelineId;
 use net_traits::image::base::Image;
 use script_traits::compositor::{ScrollSensitivity, ScrollTreeNodeId};
 use serde::Serialize;
@@ -35,6 +34,8 @@ use webrender_api::{
     SpatialId, StickyOffsetBounds, TransformStyle,
 };
 
+use super::StackingContextId;
+
 /// The factor that we multiply the blur radius by in order to inflate the boundaries of display
 /// items that involve a blur. This ensures that the display item boundaries include all the ink.
 pub static BLUR_INFLATION_FACTOR: i32 = 3;
diff --git a/components/layout/display_list/mod.rs b/components/layout/display_list/mod.rs
index aa6d3d2f500..ccd7763144f 100644
--- a/components/layout/display_list/mod.rs
+++ b/components/layout/display_list/mod.rs
@@ -2,6 +2,9 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
+use malloc_size_of_derive::MallocSizeOf;
+use serde::{Deserialize, Serialize};
+
 pub use self::builder::{
     BorderPaintingMode, DisplayListBuildState, IndexableText, StackingContextCollectionFlags,
     StackingContextCollectionState,
@@ -15,3 +18,24 @@ pub(crate) mod conversions;
 mod gradient;
 pub mod items;
 mod webrender_helpers;
+
+/// A unique ID for every stacking context.
+#[derive(Clone, Copy, Debug, Deserialize, Eq, Hash, MallocSizeOf, PartialEq, Serialize)]
+pub struct StackingContextId(
+    /// The identifier for this StackingContext, derived from the Flow's memory address
+    /// and fragment type.  As a space optimization, these are combined into a single word.
+    pub u64,
+);
+
+impl StackingContextId {
+    /// Returns the stacking context ID for the outer document/layout root.
+    #[inline]
+    pub fn root() -> StackingContextId {
+        StackingContextId(0)
+    }
+
+    pub fn next(&self) -> StackingContextId {
+        let StackingContextId(id) = *self;
+        StackingContextId(id + 1)
+    }
+}
diff --git a/components/layout/display_list/webrender_helpers.rs b/components/layout/display_list/webrender_helpers.rs
index 85c3694b98d..0ac79b4d8ca 100644
--- a/components/layout/display_list/webrender_helpers.rs
+++ b/components/layout/display_list/webrender_helpers.rs
@@ -7,9 +7,9 @@
 //           This might be achieved by sharing types between WR and Servo display lists, or
 //           completely converting layout to directly generate WebRender display lists, for example.
 
-use gfx_traits::WebRenderEpochToU16;
+use base::id::PipelineId;
+use base::WebRenderEpochToU16;
 use log::trace;
-use msg::constellation_msg::PipelineId;
 use script_traits::compositor::{
     CompositorDisplayListInfo, ScrollSensitivity, ScrollTreeNodeId, ScrollableNodeInfo,
 };
diff --git a/components/layout/flow.rs b/components/layout/flow.rs
index 29152507c12..8cdaa6d521d 100644
--- a/components/layout/flow.rs
+++ b/components/layout/flow.rs
@@ -31,10 +31,9 @@ use std::sync::atomic::Ordering;
 use std::sync::Arc;
 
 use app_units::Au;
+use base::print_tree::PrintTree;
 use bitflags::bitflags;
 use euclid::default::{Point2D, Rect, Size2D, Vector2D};
-use gfx_traits::print_tree::PrintTree;
-use gfx_traits::StackingContextId;
 use log::debug;
 use serde::ser::{SerializeStruct, Serializer};
 use serde::Serialize;
@@ -54,7 +53,9 @@ use webrender_api::units::LayoutTransform;
 use crate::block::{BlockFlow, FormattingContextType};
 use crate::context::LayoutContext;
 use crate::display_list::items::ClippingAndScrolling;
-use crate::display_list::{DisplayListBuildState, StackingContextCollectionState};
+use crate::display_list::{
+    DisplayListBuildState, StackingContextCollectionState, StackingContextId,
+};
 use crate::flex::FlexFlow;
 use crate::floats::{Floats, SpeculatedFloatPlacement};
 use crate::flow_list::{FlowList, FlowListIterator, MutFlowListIterator};
diff --git a/components/layout/fragment.rs b/components/layout/fragment.rs
index 45843627493..171c529babc 100644
--- a/components/layout/fragment.rs
+++ b/components/layout/fragment.rs
@@ -11,16 +11,15 @@ use std::sync::{Arc, Mutex};
 use std::{f32, fmt};
 
 use app_units::Au;
+use base::id::{BrowsingContextId, PipelineId};
 use bitflags::bitflags;
 use canvas_traits::canvas::{CanvasId, CanvasMsg};
 use euclid::default::{Point2D, Rect, Size2D, Vector2D};
 use gfx::text::glyph::ByteIndex;
 use gfx::text::text_run::{TextRun, TextRunSlice};
-use gfx_traits::StackingContextId;
 use html5ever::{local_name, namespace_url, ns};
 use ipc_channel::ipc::IpcSender;
 use log::debug;
-use msg::constellation_msg::{BrowsingContextId, PipelineId};
 use net_traits::image::base::{Image, ImageMetadata};
 use net_traits::image_cache::{ImageOrMetadataAvailable, UsePlaceholder};
 use range::*;
@@ -59,7 +58,7 @@ use webrender_api::{self, ImageKey};
 
 use crate::context::LayoutContext;
 use crate::display_list::items::{ClipScrollNodeIndex, OpaqueNode, BLUR_INFLATION_FACTOR};
-use crate::display_list::ToLayout;
+use crate::display_list::{StackingContextId, ToLayout};
 use crate::floats::ClearType;
 use crate::flow::{GetBaseFlow, ImmutableFlowUtils};
 use crate::flow_ref::FlowRef;
diff --git a/components/layout/inline.rs b/components/layout/inline.rs
index 5926e4b2e03..fa56f83979f 100644
--- a/components/layout/inline.rs
+++ b/components/layout/inline.rs
@@ -8,10 +8,10 @@ use std::sync::Arc;
 use std::{fmt, i32, isize, mem};
 
 use app_units::{Au, MIN_AU};
+use base::print_tree::PrintTree;
 use bitflags::bitflags;
 use euclid::default::{Point2D, Rect, Size2D};
 use gfx::font::FontMetrics;
-use gfx_traits::print_tree::PrintTree;
 use log::debug;
 use range::{int_range_index, Range, RangeIndex};
 use script_layout_interface::wrapper_traits::PseudoElementType;
diff --git a/components/layout/multicol.rs b/components/layout/multicol.rs
index 9e12a991772..ed82b41fe1c 100644
--- a/components/layout/multicol.rs
+++ b/components/layout/multicol.rs
@@ -9,8 +9,8 @@ use std::fmt;
 use std::sync::Arc;
 
 use app_units::Au;
+use base::print_tree::PrintTree;
 use euclid::default::{Point2D, Vector2D};
-use gfx_traits::print_tree::PrintTree;
 use log::{debug, trace};
 use style::logical_geometry::LogicalSize;
 use style::properties::ComputedValues;
diff --git a/components/layout/table.rs b/components/layout/table.rs
index 1821769bc79..55f19c05867 100644
--- a/components/layout/table.rs
+++ b/components/layout/table.rs
@@ -7,8 +7,8 @@
 use std::{cmp, fmt};
 
 use app_units::Au;
+use base::print_tree::PrintTree;
 use euclid::default::Point2D;
-use gfx_traits::print_tree::PrintTree;
 use log::{debug, trace};
 use serde::Serialize;
 use style::computed_values::{border_collapse, border_spacing, table_layout};
diff --git a/components/layout/table_caption.rs b/components/layout/table_caption.rs
index 398a43a7dbf..719d9a2309d 100644
--- a/components/layout/table_caption.rs
+++ b/components/layout/table_caption.rs
@@ -7,8 +7,8 @@
 use std::fmt;
 
 use app_units::Au;
+use base::print_tree::PrintTree;
 use euclid::default::Point2D;
-use gfx_traits::print_tree::PrintTree;
 use log::{debug, trace};
 use style::logical_geometry::LogicalSize;
 use style::properties::ComputedValues;
diff --git a/components/layout/table_cell.rs b/components/layout/table_cell.rs
index 013702e9401..a70ea183931 100644
--- a/components/layout/table_cell.rs
+++ b/components/layout/table_cell.rs
@@ -7,8 +7,8 @@
 use std::fmt;
 
 use app_units::Au;
+use base::print_tree::PrintTree;
 use euclid::default::{Point2D, Rect, SideOffsets2D, Size2D};
-use gfx_traits::print_tree::PrintTree;
 use log::{debug, trace};
 use script_layout_interface::wrapper_traits::ThreadSafeLayoutNode;
 use serde::Serialize;
diff --git a/components/layout/table_row.rs b/components/layout/table_row.rs
index 764386d9033..21aee72bba5 100644
--- a/components/layout/table_row.rs
+++ b/components/layout/table_row.rs
@@ -9,8 +9,8 @@ use std::fmt;
 use std::iter::{Enumerate, Peekable};
 
 use app_units::Au;
+use base::print_tree::PrintTree;
 use euclid::default::Point2D;
-use gfx_traits::print_tree::PrintTree;
 use log::{debug, warn};
 use serde::{Serialize, Serializer};
 use style::computed_values::border_collapse::T as BorderCollapse;
diff --git a/components/layout/table_rowgroup.rs b/components/layout/table_rowgroup.rs
index 345bba4a588..4a21856b9f8 100644
--- a/components/layout/table_rowgroup.rs
+++ b/components/layout/table_rowgroup.rs
@@ -8,8 +8,8 @@ use std::fmt;
 use std::iter::{Iterator, Peekable};
 
 use app_units::Au;
+use base::print_tree::PrintTree;
 use euclid::default::Point2D;
-use gfx_traits::print_tree::PrintTree;
 use log::{debug, trace};
 use serde::{Serialize, Serializer};
 use style::computed_values::{border_collapse, border_spacing};
diff --git a/components/layout/table_wrapper.rs b/components/layout/table_wrapper.rs
index 25832386566..3d5bc557561 100644
--- a/components/layout/table_wrapper.rs
+++ b/components/layout/table_wrapper.rs
@@ -16,8 +16,8 @@ use std::fmt;
 use std::ops::Add;
 
 use app_units::Au;
+use base::print_tree::PrintTree;
 use euclid::default::Point2D;
-use gfx_traits::print_tree::PrintTree;
 use log::{debug, trace};
 use serde::Serialize;
 use style::computed_values::{position, table_layout};
diff --git a/components/layout_2020/Cargo.toml b/components/layout_2020/Cargo.toml
index 5ed04e7b908..99446a0f59c 100644
--- a/components/layout_2020/Cargo.toml
+++ b/components/layout_2020/Cargo.toml
@@ -15,6 +15,7 @@ doctest = false
 [dependencies]
 app_units = { workspace = true }
 atomic_refcell = { workspace = true }
+base = { workspace = true }
 canvas_traits = { workspace = true }
 bitflags = { workspace = true }
 cssparser = { workspace = true }
@@ -27,7 +28,6 @@ gfx_traits = { workspace = true }
 html5ever = { workspace = true }
 ipc-channel = { workspace = true }
 log = { workspace = true }
-msg = { workspace = true }
 net_traits = { workspace = true }
 parking_lot = { workspace = true }
 range = { path = "../range" }
diff --git a/components/layout_2020/context.rs b/components/layout_2020/context.rs
index 500f16093b1..145f2d6591e 100644
--- a/components/layout_2020/context.rs
+++ b/components/layout_2020/context.rs
@@ -4,10 +4,10 @@
 
 use std::sync::{Arc, Mutex};
 
+use base::id::PipelineId;
 use fnv::FnvHashMap;
 use gfx::font_cache_thread::FontCacheThread;
 use gfx::font_context::FontContext;
-use msg::constellation_msg::PipelineId;
 use net_traits::image_cache::{
     ImageCache, ImageCacheResult, ImageOrMetadataAvailable, UsePlaceholder,
 };
diff --git a/components/layout_2020/display_list/mod.rs b/components/layout_2020/display_list/mod.rs
index bfa8e9c266f..d4be0e26b71 100644
--- a/components/layout_2020/display_list/mod.rs
+++ b/components/layout_2020/display_list/mod.rs
@@ -5,12 +5,12 @@
 use std::cell::{OnceCell, RefCell};
 use std::sync::Arc;
 
+use base::id::BrowsingContextId;
+use base::WebRenderEpochToU16;
 use embedder_traits::Cursor;
 use euclid::{Point2D, SideOffsets2D, Size2D};
 use fnv::FnvHashMap;
 use gfx::text::glyph::GlyphStore;
-use gfx_traits::WebRenderEpochToU16;
-use msg::constellation_msg::BrowsingContextId;
 use net_traits::image_cache::UsePlaceholder;
 use script_traits::compositor::{CompositorDisplayListInfo, ScrollSensitivity, ScrollTreeNodeId};
 use servo_geometry::MaxRect;
diff --git a/components/layout_2020/display_list/stacking_context.rs b/components/layout_2020/display_list/stacking_context.rs
index 407d2fb4adc..0b37949b1b8 100644
--- a/components/layout_2020/display_list/stacking_context.rs
+++ b/components/layout_2020/display_list/stacking_context.rs
@@ -5,9 +5,9 @@
 use std::cell::RefCell;
 use std::mem;
 
+use base::print_tree::PrintTree;
 use euclid::default::Rect;
 use euclid::SideOffsets2D;
-use gfx_traits::print_tree::PrintTree;
 use log::warn;
 use script_traits::compositor::{ScrollSensitivity, ScrollTreeNodeId, ScrollableNodeInfo};
 use servo_arc::Arc as ServoArc;
diff --git a/components/layout_2020/dom.rs b/components/layout_2020/dom.rs
index 5d75317f75d..24d4647e0a5 100644
--- a/components/layout_2020/dom.rs
+++ b/components/layout_2020/dom.rs
@@ -6,8 +6,8 @@ use std::marker::PhantomData;
 use std::sync::{Arc, Mutex};
 
 use atomic_refcell::{AtomicRef, AtomicRefCell, AtomicRefMut};
+use base::id::{BrowsingContextId, PipelineId};
 use html5ever::{local_name, namespace_url, ns};
-use msg::constellation_msg::{BrowsingContextId, PipelineId};
 use net_traits::image::base::Image as NetImage;
 use script_layout_interface::wrapper_traits::{
     LayoutDataTrait, LayoutNode, ThreadSafeLayoutElement, ThreadSafeLayoutNode,
diff --git a/components/layout_2020/fragment_tree/base_fragment.rs b/components/layout_2020/fragment_tree/base_fragment.rs
index 3acee7a7cfe..3dbb530a4c6 100644
--- a/components/layout_2020/fragment_tree/base_fragment.rs
+++ b/components/layout_2020/fragment_tree/base_fragment.rs
@@ -3,7 +3,7 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 use bitflags::bitflags;
-use gfx_traits::{combine_id_with_fragment_type, FragmentType};
+use script_layout_interface::{combine_id_with_fragment_type, FragmentType};
 use serde::Serialize;
 use style::dom::OpaqueNode;
 use style::selector_parser::PseudoElement;
diff --git a/components/layout_2020/fragment_tree/box_fragment.rs b/components/layout_2020/fragment_tree/box_fragment.rs
index ab75a2a6b6f..b44b2bc14b1 100644
--- a/components/layout_2020/fragment_tree/box_fragment.rs
+++ b/components/layout_2020/fragment_tree/box_fragment.rs
@@ -3,7 +3,7 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 use app_units::Au;
-use gfx_traits::print_tree::PrintTree;
+use base::print_tree::PrintTree;
 use serde::Serialize;
 use servo_arc::Arc as ServoArc;
 use style::computed_values::overflow_x::T as ComputedOverflow;
diff --git a/components/layout_2020/fragment_tree/fragment.rs b/components/layout_2020/fragment_tree/fragment.rs
index 2aaf4775499..a5dc9b0433c 100644
--- a/components/layout_2020/fragment_tree/fragment.rs
+++ b/components/layout_2020/fragment_tree/fragment.rs
@@ -5,10 +5,10 @@
 use std::sync::Arc;
 
 use app_units::Au;
+use base::id::{BrowsingContextId, PipelineId};
+use base::print_tree::PrintTree;
 use gfx::font::FontMetrics;
 use gfx::text::glyph::GlyphStore;
-use gfx_traits::print_tree::PrintTree;
-use msg::constellation_msg::{BrowsingContextId, PipelineId};
 use serde::Serialize;
 use servo_arc::Arc as ServoArc;
 use style::properties::ComputedValues;
diff --git a/components/layout_2020/fragment_tree/fragment_tree.rs b/components/layout_2020/fragment_tree/fragment_tree.rs
index 6ea98204fb4..77d07a65847 100644
--- a/components/layout_2020/fragment_tree/fragment_tree.rs
+++ b/components/layout_2020/fragment_tree/fragment_tree.rs
@@ -3,9 +3,9 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 use app_units::Au;
+use base::print_tree::PrintTree;
 use euclid::default::{Point2D, Rect, Size2D};
 use fxhash::FxHashSet;
-use gfx_traits::print_tree::PrintTree;
 use script_traits::compositor::ScrollSensitivity;
 use serde::Serialize;
 use style::animation::AnimationSetKey;
diff --git a/components/layout_2020/fragment_tree/positioning_fragment.rs b/components/layout_2020/fragment_tree/positioning_fragment.rs
index 2865e58121e..7da428bf064 100644
--- a/components/layout_2020/fragment_tree/positioning_fragment.rs
+++ b/components/layout_2020/fragment_tree/positioning_fragment.rs
@@ -2,7 +2,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
-use gfx_traits::print_tree::PrintTree;
+use base::print_tree::PrintTree;
 use serde::Serialize;
 use servo_arc::Arc as ServoArc;
 use style::logical_geometry::WritingMode;
diff --git a/components/layout_2020/replaced.rs b/components/layout_2020/replaced.rs
index 7f3f7743c1c..ac3f1621d85 100644
--- a/components/layout_2020/replaced.rs
+++ b/components/layout_2020/replaced.rs
@@ -6,10 +6,10 @@ use std::fmt;
 use std::sync::{Arc, Mutex};
 
 use app_units::Au;
+use base::id::{BrowsingContextId, PipelineId};
 use canvas_traits::canvas::{CanvasId, CanvasMsg, FromLayoutMsg};
 use data_url::DataUrl;
 use ipc_channel::ipc::{self, IpcSender};
-use msg::constellation_msg::{BrowsingContextId, PipelineId};
 use net_traits::image::base::Image;
 use net_traits::image_cache::{ImageOrMetadataAvailable, UsePlaceholder};
 use serde::Serialize;
diff --git a/components/layout_thread/Cargo.toml b/components/layout_thread/Cargo.toml
index 97fc689dd2d..978b597212b 100644
--- a/components/layout_thread/Cargo.toml
+++ b/components/layout_thread/Cargo.toml
@@ -12,6 +12,7 @@ path = "lib.rs"
 
 [dependencies]
 app_units = { workspace = true }
+base = { workspace = true }
 crossbeam-channel = { workspace = true }
 embedder_traits = { workspace = true }
 euclid = { workspace = true }
@@ -26,7 +27,6 @@ lazy_static = { workspace = true }
 log = { workspace = true }
 malloc_size_of = { workspace = true }
 metrics = { path = "../metrics" }
-msg = { workspace = true }
 net_traits = { workspace = true }
 parking_lot = { workspace = true }
 profile_traits = { workspace = true }
diff --git a/components/layout_thread/lib.rs b/components/layout_thread/lib.rs
index c56d0ee1bd8..e279f10221d 100644
--- a/components/layout_thread/lib.rs
+++ b/components/layout_thread/lib.rs
@@ -17,6 +17,8 @@ use std::sync::atomic::{AtomicUsize, Ordering};
 use std::sync::{Arc, Mutex};
 
 use app_units::Au;
+use base::id::{BrowsingContextId, PipelineId};
+use base::Epoch;
 use embedder_traits::resources::{self, Resource};
 use euclid::default::{Point2D as UntypedPoint2D, Rect as UntypedRect, Size2D as UntypedSize2D};
 use euclid::{Point2D, Rect, Scale, Size2D};
@@ -25,7 +27,6 @@ use fxhash::{FxHashMap, FxHashSet};
 use gfx::font;
 use gfx::font_cache_thread::FontCacheThread;
 use gfx::font_context::FontContext;
-use gfx_traits::{node_id_from_scroll_id, Epoch};
 use histogram::Histogram;
 use ipc_channel::ipc::{self, IpcSender};
 use ipc_channel::router::ROUTER;
@@ -52,7 +53,6 @@ use lazy_static::lazy_static;
 use log::{debug, error, trace, warn};
 use malloc_size_of::{MallocSizeOf, MallocSizeOfOps};
 use metrics::{PaintTimeMetrics, ProfilerMetadataFactory};
-use msg::constellation_msg::{BrowsingContextId, PipelineId};
 use net_traits::image_cache::{ImageCache, UsePlaceholder};
 use parking_lot::RwLock;
 use profile_traits::mem::{Report, ReportKind};
@@ -63,8 +63,8 @@ use profile_traits::time::{
 use script::layout_dom::{ServoLayoutDocument, ServoLayoutElement, ServoLayoutNode};
 use script_layout_interface::wrapper_traits::LayoutNode;
 use script_layout_interface::{
-    Layout, LayoutConfig, LayoutFactory, NodesFromPointQueryType, OffsetParentResponse, Reflow,
-    ReflowComplete, ReflowGoal, ScriptReflow, TrustedNodeAddress,
+    node_id_from_scroll_id, Layout, LayoutConfig, LayoutFactory, NodesFromPointQueryType,
+    OffsetParentResponse, Reflow, ReflowComplete, ReflowGoal, ScriptReflow, TrustedNodeAddress,
 };
 use script_traits::{
     ConstellationControlMsg, DrawAPaintImageResult, IFrameSizeMsg, LayoutControlMsg,
diff --git a/components/layout_thread_2020/Cargo.toml b/components/layout_thread_2020/Cargo.toml
index c5010281ae8..633b903e509 100644
--- a/components/layout_thread_2020/Cargo.toml
+++ b/components/layout_thread_2020/Cargo.toml
@@ -12,6 +12,7 @@ path = "lib.rs"
 
 [dependencies]
 app_units = { workspace = true }
+base = { workspace = true }
 crossbeam-channel = { workspace = true }
 embedder_traits = { workspace = true }
 euclid = { workspace = true }
@@ -25,7 +26,6 @@ lazy_static = { workspace = true }
 log = { workspace = true }
 malloc_size_of = { workspace = true }
 metrics = { path = "../metrics" }
-msg = { workspace = true }
 net_traits = { workspace = true }
 parking_lot = { workspace = true }
 profile_traits = { workspace = true }
diff --git a/components/layout_thread_2020/lib.rs b/components/layout_thread_2020/lib.rs
index a506a21859e..048a5d86216 100644
--- a/components/layout_thread_2020/lib.rs
+++ b/components/layout_thread_2020/lib.rs
@@ -16,6 +16,8 @@ use std::sync::atomic::{AtomicUsize, Ordering};
 use std::sync::{Arc, Mutex};
 
 use app_units::Au;
+use base::id::{BrowsingContextId, PipelineId};
+use base::Epoch;
 use embedder_traits::resources::{self, Resource};
 use euclid::default::{Point2D as UntypedPoint2D, Rect as UntypedRect, Size2D as UntypedSize2D};
 use euclid::{Point2D, Scale, Size2D, Vector2D};
@@ -23,7 +25,6 @@ use fnv::FnvHashMap;
 use fxhash::FxHashMap;
 use gfx::font_cache_thread::FontCacheThread;
 use gfx::font_context::FontContext;
-use gfx_traits::{node_id_from_scroll_id, Epoch};
 use ipc_channel::ipc::{self, IpcSender};
 use ipc_channel::router::ROUTER;
 use layout::context::LayoutContext;
@@ -39,7 +40,6 @@ use lazy_static::lazy_static;
 use log::{debug, error, warn};
 use malloc_size_of::{MallocSizeOf, MallocSizeOfOps};
 use metrics::{PaintTimeMetrics, ProfilerMetadataFactory};
-use msg::constellation_msg::{BrowsingContextId, PipelineId};
 use net_traits::image_cache::{ImageCache, UsePlaceholder};
 use parking_lot::RwLock;
 use profile_traits::mem::{Report, ReportKind};
@@ -49,8 +49,8 @@ use profile_traits::time::{
 };
 use script::layout_dom::{ServoLayoutDocument, ServoLayoutElement, ServoLayoutNode};
 use script_layout_interface::{
-    Layout, LayoutConfig, LayoutFactory, NodesFromPointQueryType, OffsetParentResponse,
-    ReflowComplete, ReflowGoal, ScriptReflow, TrustedNodeAddress,
+    node_id_from_scroll_id, Layout, LayoutConfig, LayoutFactory, NodesFromPointQueryType,
+    OffsetParentResponse, ReflowComplete, ReflowGoal, ScriptReflow, TrustedNodeAddress,
 };
 use script_traits::{
     ConstellationControlMsg, DrawAPaintImageResult, IFrameSizeMsg, LayoutControlMsg,
diff --git a/components/metrics/Cargo.toml b/components/metrics/Cargo.toml
index 08701edf372..888fabc2dd6 100644
--- a/components/metrics/Cargo.toml
+++ b/components/metrics/Cargo.toml
@@ -11,12 +11,12 @@ name = "metrics"
 path = "lib.rs"
 
 [dependencies]
+base = { workspace = true }
 gfx_traits = { workspace = true }
 ipc-channel = { workspace = true }
 log = { workspace = true }
 malloc_size_of = { workspace = true }
 malloc_size_of_derive = { workspace = true }
-msg = { workspace = true }
 profile_traits = { workspace = true }
 script_traits = { workspace = true }
 servo_config = { path = "../config" }
diff --git a/components/metrics/lib.rs b/components/metrics/lib.rs
index 7aa42f365ae..3effde8cac0 100644
--- a/components/metrics/lib.rs
+++ b/components/metrics/lib.rs
@@ -7,11 +7,11 @@ use std::cmp::Ordering;
 use std::collections::HashMap;
 use std::time::{Duration, SystemTime, UNIX_EPOCH};
 
-use gfx_traits::Epoch;
+use base::id::PipelineId;
+use base::Epoch;
 use ipc_channel::ipc::IpcSender;
 use log::warn;
 use malloc_size_of_derive::MallocSizeOf;
-use msg::constellation_msg::PipelineId;
 use profile_traits::time::{send_profile_data, ProfilerCategory, ProfilerChan, TimerMetadata};
 use script_traits::{ConstellationControlMsg, LayoutMsg, ProgressiveWebMetricType};
 use servo_config::opts;
diff --git a/components/net/Cargo.toml b/components/net/Cargo.toml
index 01da269cd0b..bce568c034a 100644
--- a/components/net/Cargo.toml
+++ b/components/net/Cargo.toml
@@ -16,6 +16,7 @@ doctest = false
 [dependencies]
 async-recursion = "0.3.2"
 async-tungstenite = { workspace = true }
+base = { workspace = true }
 base64 = { workspace = true }
 brotli = "3"
 bytes = "1"
@@ -42,7 +43,6 @@ malloc_size_of = { workspace = true }
 malloc_size_of_derive = { workspace = true }
 mime = { workspace = true }
 mime_guess = { workspace = true }
-msg = { workspace = true }
 net_traits = { workspace = true }
 percent-encoding = { workspace = true }
 pixels = { path = "../pixels" }
diff --git a/components/net/http_loader.rs b/components/net/http_loader.rs
index 9332eca67b1..32b309d0f8c 100644
--- a/components/net/http_loader.rs
+++ b/components/net/http_loader.rs
@@ -9,6 +9,7 @@ use std::sync::{Arc as StdArc, Condvar, Mutex, RwLock};
 use std::time::{Duration, SystemTime, UNIX_EPOCH};
 
 use async_recursion::async_recursion;
+use base::id::{HistoryStateId, PipelineId};
 use crossbeam_channel::Sender;
 use devtools_traits::{
     ChromeToDevtoolsControlMsg, DevtoolsControlMsg, HttpRequest as DevtoolsHttpRequest,
@@ -32,7 +33,6 @@ use hyper_serde::Serde;
 use ipc_channel::ipc::{self, IpcSender};
 use ipc_channel::router::ROUTER;
 use log::{debug, error, info, log_enabled, warn};
-use msg::constellation_msg::{HistoryStateId, PipelineId};
 use net_traits::pub_domains::reg_suffix;
 use net_traits::quality::{quality_to_value, Quality, QualityItem};
 use net_traits::request::Origin::Origin as SpecificOrigin;
diff --git a/components/net/tests/fetch.rs b/components/net/tests/fetch.rs
index 6faf1d362e3..5f04f01cf46 100644
--- a/components/net/tests/fetch.rs
+++ b/components/net/tests/fetch.rs
@@ -11,6 +11,7 @@ use std::sync::atomic::{AtomicUsize, Ordering};
 use std::sync::{Arc, Mutex, Weak};
 use std::time::{Duration, SystemTime};
 
+use base::id::TEST_PIPELINE_ID;
 use crossbeam_channel::{unbounded, Sender};
 use devtools_traits::{HttpRequest as DevtoolsHttpRequest, HttpResponse as DevtoolsHttpResponse};
 use headers::{
@@ -22,7 +23,6 @@ use http::header::{self, HeaderMap, HeaderName, HeaderValue};
 use http::{Method, StatusCode};
 use hyper::{Body, Request as HyperRequest, Response as HyperResponse};
 use mime::{self, Mime};
-use msg::constellation_msg::TEST_PIPELINE_ID;
 use net::fetch::cors_cache::CorsCache;
 use net::fetch::methods::{self, CancellationListener, FetchContext};
 use net::filemanager_thread::FileManager;
diff --git a/components/net/tests/http_cache.rs b/components/net/tests/http_cache.rs
index 4acdc402043..6d7848fad5e 100644
--- a/components/net/tests/http_cache.rs
+++ b/components/net/tests/http_cache.rs
@@ -2,9 +2,9 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
+use base::id::TEST_PIPELINE_ID;
 use http::header::{HeaderValue, EXPIRES};
 use http::StatusCode;
-use msg::constellation_msg::TEST_PIPELINE_ID;
 use net::http_cache::HttpCache;
 use net_traits::request::{Origin, Referrer, Request};
 use net_traits::response::{HttpsState, Response, ResponseBody};
diff --git a/components/net/tests/http_loader.rs b/components/net/tests/http_loader.rs
index 324b75daa7f..1db85d44ecc 100644
--- a/components/net/tests/http_loader.rs
+++ b/components/net/tests/http_loader.rs
@@ -11,6 +11,7 @@ use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::{Arc, Mutex, RwLock};
 use std::time::Duration;
 
+use base::id::TEST_PIPELINE_ID;
 use cookie_rs::Cookie as CookiePair;
 use crossbeam_channel::{unbounded, Receiver};
 use devtools_traits::{
@@ -29,7 +30,6 @@ use http::{Method, StatusCode};
 use hyper::{Body, Request as HyperRequest, Response as HyperResponse};
 use ipc_channel::ipc;
 use ipc_channel::router::ROUTER;
-use msg::constellation_msg::TEST_PIPELINE_ID;
 use net::cookie::Cookie;
 use net::cookie_storage::CookieStorage;
 use net::http_loader::determine_requests_referrer;
diff --git a/components/script/Cargo.toml b/components/script/Cargo.toml
index 1fc2f1a69cc..45926d07f40 100644
--- a/components/script/Cargo.toml
+++ b/components/script/Cargo.toml
@@ -31,7 +31,9 @@ accountable-refcell = { workspace = true, optional = true }
 app_units = { workspace = true }
 arrayvec = { workspace = true }
 atomic_refcell = { workspace = true }
+background_hang_monitor_api = { workspace = true }
 backtrace = { workspace = true }
+base = { workspace = true }
 base64 = { workspace = true }
 bitflags = { workspace = true }
 bluetooth_traits = { workspace = true }
@@ -74,7 +76,6 @@ media = { path = "../media" }
 metrics = { path = "../metrics" }
 mime = { workspace = true }
 mime_guess = { workspace = true }
-msg = { workspace = true }
 net_traits = { workspace = true }
 num_cpus = { workspace = true }
 num-traits = { workspace = true }
diff --git a/components/script/animations.rs b/components/script/animations.rs
index 4edb20a92a8..45e88734e75 100644
--- a/components/script/animations.rs
+++ b/components/script/animations.rs
@@ -6,10 +6,10 @@
 
 use std::cell::Cell;
 
+use base::id::PipelineId;
 use cssparser::ToCss;
 use fxhash::{FxHashMap, FxHashSet};
 use libc::c_void;
-use msg::constellation_msg::PipelineId;
 use script_traits::{AnimationState as AnimationsPresentState, ScriptMsg, UntrustedNodeAddress};
 use serde::{Deserialize, Serialize};
 use style::animation::{
diff --git a/components/script/devtools.rs b/components/script/devtools.rs
index d83e9fecdc6..1bb34ecdb7c 100644
--- a/components/script/devtools.rs
+++ b/components/script/devtools.rs
@@ -5,6 +5,7 @@
 use std::rc::Rc;
 use std::str;
 
+use base::id::PipelineId;
 use devtools_traits::{
     AutoMargins, ComputedNodeLayout, EvaluateJSReply, Modification, NodeInfo, TimelineMarker,
     TimelineMarkerType,
@@ -12,7 +13,6 @@ use devtools_traits::{
 use ipc_channel::ipc::IpcSender;
 use js::jsval::UndefinedValue;
 use js::rust::ToString;
-use msg::constellation_msg::PipelineId;
 use uuid::Uuid;
 
 use crate::dom::bindings::codegen::Bindings::CSSStyleDeclarationBinding::CSSStyleDeclarationMethods;
diff --git a/components/script/dom/audiocontext.rs b/components/script/dom/audiocontext.rs
index a82ff1e93a3..e3be006aced 100644
--- a/components/script/dom/audiocontext.rs
+++ b/components/script/dom/audiocontext.rs
@@ -4,9 +4,9 @@
 
 use std::rc::Rc;
 
+use base::id::PipelineId;
 use dom_struct::dom_struct;
 use js::rust::HandleObject;
-use msg::constellation_msg::PipelineId;
 use servo_media::audio::context::{LatencyCategory, ProcessingState, RealTimeAudioContextOptions};
 
 use crate::dom::baseaudiocontext::{BaseAudioContext, BaseAudioContextOptions};
diff --git a/components/script/dom/baseaudiocontext.rs b/components/script/dom/baseaudiocontext.rs
index e47e2e02b95..e68534c5f76 100644
--- a/components/script/dom/baseaudiocontext.rs
+++ b/components/script/dom/baseaudiocontext.rs
@@ -8,10 +8,10 @@ use std::collections::{HashMap, VecDeque};
 use std::rc::Rc;
 use std::sync::{Arc, Mutex};
 
+use base::id::PipelineId;
 use dom_struct::dom_struct;
 use js::rust::CustomAutoRooterGuard;
 use js::typedarray::ArrayBuffer;
-use msg::constellation_msg::PipelineId;
 use servo_media::audio::context::{
     AudioContext, AudioContextOptions, OfflineAudioContextOptions, ProcessingState,
     RealTimeAudioContextOptions,
diff --git a/components/script/dom/bindings/structuredclone.rs b/components/script/dom/bindings/structuredclone.rs
index 209a499ee59..d63299a5bab 100644
--- a/components/script/dom/bindings/structuredclone.rs
+++ b/components/script/dom/bindings/structuredclone.rs
@@ -8,6 +8,7 @@ use std::collections::HashMap;
 use std::os::raw;
 use std::ptr;
 
+use base::id::{BlobId, MessagePortId};
 use js::glue::{
     CopyJSStructuredCloneData, DeleteJSAutoStructuredCloneBuffer, GetLengthOfJSStructuredCloneData,
     NewJSAutoStructuredCloneBuffer, WriteBytesToJSStructuredCloneData,
@@ -22,7 +23,6 @@ use js::jsapi::{
 use js::jsval::UndefinedValue;
 use js::rust::wrappers::{JS_ReadStructuredClone, JS_WriteStructuredClone};
 use js::rust::{CustomAutoRooterGuard, HandleValue, MutableHandleValue};
-use msg::constellation_msg::{BlobId, MessagePortId};
 use script_traits::serializable::BlobImpl;
 use script_traits::transferable::MessagePortImpl;
 use script_traits::StructuredSerializedData;
diff --git a/components/script/dom/blob.rs b/components/script/dom/blob.rs
index 7cdb6384ed1..0cc13392f12 100644
--- a/components/script/dom/blob.rs
+++ b/components/script/dom/blob.rs
@@ -7,11 +7,11 @@ use std::num::NonZeroU32;
 use std::ptr::NonNull;
 use std::rc::Rc;
 
+use base::id::{BlobId, BlobIndex, PipelineNamespaceId};
 use dom_struct::dom_struct;
 use encoding_rs::UTF_8;
 use js::jsapi::JSObject;
 use js::rust::HandleObject;
-use msg::constellation_msg::{BlobId, BlobIndex, PipelineNamespaceId};
 use net_traits::filemanager_thread::RelativePos;
 use script_traits::serializable::BlobImpl;
 use uuid::Uuid;
diff --git a/components/script/dom/dedicatedworkerglobalscope.rs b/components/script/dom/dedicatedworkerglobalscope.rs
index b8647c305ce..e340621af71 100644
--- a/components/script/dom/dedicatedworkerglobalscope.rs
+++ b/components/script/dom/dedicatedworkerglobalscope.rs
@@ -7,6 +7,7 @@ use std::sync::atomic::AtomicBool;
 use std::sync::Arc;
 use std::thread::{self, JoinHandle};
 
+use base::id::{BrowsingContextId, PipelineId, TopLevelBrowsingContextId};
 use crossbeam_channel::{unbounded, Receiver, Sender};
 use devtools_traits::DevtoolScriptControlMsg;
 use dom_struct::dom_struct;
@@ -15,7 +16,6 @@ use ipc_channel::router::ROUTER;
 use js::jsapi::{Heap, JSContext, JSObject, JS_AddInterruptCallback};
 use js::jsval::UndefinedValue;
 use js::rust::{CustomAutoRooter, CustomAutoRooterGuard, HandleValue};
-use msg::constellation_msg::{BrowsingContextId, PipelineId, TopLevelBrowsingContextId};
 use net_traits::image_cache::ImageCache;
 use net_traits::request::{
     CredentialsMode, Destination, ParserMetadata, Referrer, RequestBuilder, RequestMode,
diff --git a/components/script/dom/dissimilaroriginwindow.rs b/components/script/dom/dissimilaroriginwindow.rs
index ebe33bad95a..51cad369282 100644
--- a/components/script/dom/dissimilaroriginwindow.rs
+++ b/components/script/dom/dissimilaroriginwindow.rs
@@ -2,11 +2,11 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
+use base::id::PipelineId;
 use dom_struct::dom_struct;
 use js::jsapi::{Heap, JSObject};
 use js::jsval::{JSVal, UndefinedValue};
 use js::rust::{CustomAutoRooter, CustomAutoRooterGuard, HandleValue};
-use msg::constellation_msg::PipelineId;
 use script_traits::{ScriptMsg, StructuredSerializedData};
 use servo_url::ServoUrl;
 
diff --git a/components/script/dom/document.rs b/components/script/dom/document.rs
index dc55761b02f..f58f9472958 100644
--- a/components/script/dom/document.rs
+++ b/components/script/dom/document.rs
@@ -13,6 +13,7 @@ use std::rc::Rc;
 use std::slice::from_ref;
 use std::time::{Duration, Instant};
 
+use base::id::BrowsingContextId;
 use canvas_traits::webgl::{self, WebGLContextId, WebGLMsg};
 use content_security_policy::{self as csp, CspList};
 use cookie::Cookie;
@@ -33,7 +34,6 @@ use metrics::{
     ProgressiveWebMetric,
 };
 use mime::{self, Mime};
-use msg::constellation_msg::BrowsingContextId;
 use net_traits::pub_domains::is_pub_domain;
 use net_traits::request::RequestBuilder;
 use net_traits::response::HttpsState;
diff --git a/components/script/dom/element.rs b/components/script/dom/element.rs
index 12dc2af872e..e91a24e2ddf 100644
--- a/components/script/dom/element.rs
+++ b/components/script/dom/element.rs
@@ -15,6 +15,7 @@ use std::{fmt, mem};
 use cssparser::match_ignore_ascii_case;
 use devtools_traits::AttrInfo;
 use dom_struct::dom_struct;
+use embedder_traits::InputMethodType;
 use euclid::default::{Rect, Size2D};
 use html5ever::serialize::TraversalScope::{ChildrenOnly, IncludeNode};
 use html5ever::serialize::{SerializeOpts, TraversalScope};
@@ -25,7 +26,6 @@ use html5ever::{
 use js::jsapi::Heap;
 use js::jsval::JSVal;
 use js::rust::HandleObject;
-use msg::constellation_msg::InputMethodType;
 use net_traits::request::CorsSettings;
 use net_traits::ReferrerPolicy;
 use script_layout_interface::ReflowGoal;
diff --git a/components/script/dom/globalscope.rs b/components/script/dom/globalscope.rs
index 32febf8ab8e..7586a58793e 100644
--- a/components/script/dom/globalscope.rs
+++ b/components/script/dom/globalscope.rs
@@ -14,6 +14,10 @@ use std::thread::JoinHandle;
 use std::time::Instant;
 use std::{mem, ptr};
 
+use base::id::{
+    BlobId, BroadcastChannelRouterId, MessagePortId, MessagePortRouterId, PipelineId,
+    ServiceWorkerId, ServiceWorkerRegistrationId,
+};
 use content_security_policy::CspList;
 use crossbeam_channel::Sender;
 use devtools_traits::{PageError, ScriptToDevtoolsControlMsg};
@@ -34,10 +38,6 @@ use js::rust::{
     MutableHandleValue, ParentRuntime, Runtime,
 };
 use js::{JSCLASS_IS_DOMJSCLASS, JSCLASS_IS_GLOBAL};
-use msg::constellation_msg::{
-    BlobId, BroadcastChannelRouterId, MessagePortId, MessagePortRouterId, PipelineId,
-    ServiceWorkerId, ServiceWorkerRegistrationId,
-};
 use net_traits::blob_url_store::{get_blob_origin, BlobBuf};
 use net_traits::filemanager_thread::{
     FileManagerResult, FileManagerThreadMsg, ReadFileProgress, RelativePos,
diff --git a/components/script/dom/history.rs b/components/script/dom/history.rs
index 15a02fa64c1..f0be9b8ceac 100644
--- a/components/script/dom/history.rs
+++ b/components/script/dom/history.rs
@@ -5,15 +5,15 @@
 use std::cell::Cell;
 use std::cmp::Ordering;
 
+use base::id::HistoryStateId;
 use dom_struct::dom_struct;
 use js::jsapi::Heap;
 use js::jsval::{JSVal, NullValue, UndefinedValue};
 use js::rust::HandleValue;
-use msg::constellation_msg::{HistoryStateId, TraversalDirection};
 use net_traits::{CoreResourceMsg, IpcSend};
 use profile_traits::ipc;
 use profile_traits::ipc::channel;
-use script_traits::{ScriptMsg, StructuredSerializedData};
+use script_traits::{ScriptMsg, StructuredSerializedData, TraversalDirection};
 use servo_url::ServoUrl;
 
 use crate::dom::bindings::codegen::Bindings::HistoryBinding::HistoryMethods;
diff --git a/components/script/dom/htmliframeelement.rs b/components/script/dom/htmliframeelement.rs
index cb84aa7bb52..0ccf0fa7661 100644
--- a/components/script/dom/htmliframeelement.rs
+++ b/components/script/dom/htmliframeelement.rs
@@ -4,11 +4,11 @@
 
 use std::cell::Cell;
 
+use base::id::{BrowsingContextId, PipelineId, TopLevelBrowsingContextId};
 use bitflags::bitflags;
 use dom_struct::dom_struct;
 use html5ever::{local_name, namespace_url, ns, LocalName, Prefix};
 use js::rust::HandleObject;
-use msg::constellation_msg::{BrowsingContextId, PipelineId, TopLevelBrowsingContextId};
 use profile_traits::ipc as ProfiledIpc;
 use script_layout_interface::ReflowGoal;
 use script_traits::IFrameSandboxState::{IFrameSandboxed, IFrameUnsandboxed};
diff --git a/components/script/dom/htmlimageelement.rs b/components/script/dom/htmlimageelement.rs
index d2bb0d57408..96d4b1183cd 100644
--- a/components/script/dom/htmlimageelement.rs
+++ b/components/script/dom/htmlimageelement.rs
@@ -9,6 +9,7 @@ use std::sync::{Arc, Mutex};
 use std::{char, i32, mem};
 
 use app_units::{Au, AU_PER_PX};
+use base::id::PipelineId;
 use cssparser::{Parser, ParserInput};
 use dom_struct::dom_struct;
 use euclid::Point2D;
@@ -19,7 +20,6 @@ use ipc_channel::router::ROUTER;
 use js::jsapi::JSAutoRealm;
 use js::rust::HandleObject;
 use mime::{self, Mime};
-use msg::constellation_msg::PipelineId;
 use net_traits::image::base::{Image, ImageMetadata};
 use net_traits::image_cache::{
     CorsStatus, ImageCache, ImageCacheResult, ImageOrMetadataAvailable, ImageResponse,
diff --git a/components/script/dom/htmlinputelement.rs b/components/script/dom/htmlinputelement.rs
index 40315c3ecdf..eec9ae0684a 100755
--- a/components/script/dom/htmlinputelement.rs
+++ b/components/script/dom/htmlinputelement.rs
@@ -11,7 +11,7 @@ use std::{f64, ptr};
 use chrono::naive::{NaiveDate, NaiveDateTime};
 use chrono::{DateTime, Datelike, Weekday};
 use dom_struct::dom_struct;
-use embedder_traits::FilterPattern;
+use embedder_traits::{FilterPattern, InputMethodType};
 use encoding_rs::Encoding;
 use html5ever::{local_name, namespace_url, ns, LocalName, Prefix};
 use js::jsapi::{
@@ -21,7 +21,6 @@ use js::jsapi::{
 use js::jsval::UndefinedValue;
 use js::rust::jsapi_wrapped::{ExecuteRegExpNoStatics, ObjectIsRegExp};
 use js::rust::{HandleObject, MutableHandleObject};
-use msg::constellation_msg::InputMethodType;
 use net_traits::blob_url_store::get_blob_origin;
 use net_traits::filemanager_thread::FileManagerThreadMsg;
 use net_traits::{CoreResourceMsg, IpcSend};
diff --git a/components/script/dom/htmlscriptelement.rs b/components/script/dom/htmlscriptelement.rs
index d0a59070cb6..e0563f91bf3 100644
--- a/components/script/dom/htmlscriptelement.rs
+++ b/components/script/dom/htmlscriptelement.rs
@@ -12,6 +12,7 @@ use std::ptr;
 use std::rc::Rc;
 use std::sync::{Arc, Mutex};
 
+use base::id::PipelineId;
 use content_security_policy as csp;
 use dom_struct::dom_struct;
 use encoding_rs::Encoding;
@@ -24,7 +25,6 @@ use js::rust::{
     transform_str_to_source_text, CompileOptionsWrapper, FinishOffThreadStencil, HandleObject,
     Stencil,
 };
-use msg::constellation_msg::PipelineId;
 use net_traits::request::{
     CorsSettings, CredentialsMode, Destination, ParserMetadata, RequestBuilder,
 };
diff --git a/components/script/dom/messageport.rs b/components/script/dom/messageport.rs
index 02ecae8e2b1..c7086c9403c 100644
--- a/components/script/dom/messageport.rs
+++ b/components/script/dom/messageport.rs
@@ -8,10 +8,10 @@ use std::convert::TryInto;
 use std::num::NonZeroU32;
 use std::rc::Rc;
 
+use base::id::{MessagePortId, MessagePortIndex, PipelineNamespaceId};
 use dom_struct::dom_struct;
 use js::jsapi::{Heap, JSObject, MutableHandleObject};
 use js::rust::{CustomAutoRooter, CustomAutoRooterGuard, HandleValue};
-use msg::constellation_msg::{MessagePortId, MessagePortIndex, PipelineNamespaceId};
 use script_traits::PortMessageTask;
 
 use crate::dom::bindings::codegen::Bindings::EventHandlerBinding::EventHandlerNonNull;
diff --git a/components/script/dom/node.rs b/components/script/dom/node.rs
index 19178806944..3531fb1b9f3 100644
--- a/components/script/dom/node.rs
+++ b/components/script/dom/node.rs
@@ -13,6 +13,7 @@ use std::sync::Arc as StdArc;
 use std::{cmp, iter};
 
 use app_units::Au;
+use base::id::{BrowsingContextId, PipelineId};
 use bitflags::bitflags;
 use devtools_traits::NodeInfo;
 use dom_struct::dom_struct;
@@ -22,7 +23,6 @@ use js::jsapi::JSObject;
 use js::rust::HandleObject;
 use libc::{self, c_void, uintptr_t};
 use malloc_size_of::{MallocSizeOf, MallocSizeOfOps};
-use msg::constellation_msg::{BrowsingContextId, PipelineId};
 use net_traits::image::base::{Image, ImageMetadata};
 use script_layout_interface::{
     GenericLayoutData, HTMLCanvasData, HTMLMediaData, LayoutElementType, LayoutNodeType, QueryMsg,
diff --git a/components/script/dom/offlineaudiocontext.rs b/components/script/dom/offlineaudiocontext.rs
index fcdffddb449..0d47380ab61 100644
--- a/components/script/dom/offlineaudiocontext.rs
+++ b/components/script/dom/offlineaudiocontext.rs
@@ -7,9 +7,9 @@ use std::rc::Rc;
 use std::sync::{mpsc, Arc, Mutex};
 use std::thread::Builder;
 
+use base::id::PipelineId;
 use dom_struct::dom_struct;
 use js::rust::HandleObject;
-use msg::constellation_msg::PipelineId;
 use servo_media::audio::context::OfflineAudioContextOptions as ServoMediaOfflineAudioContextOptions;
 
 use crate::dom::audiobuffer::{AudioBuffer, MAX_SAMPLE_RATE, MIN_SAMPLE_RATE};
diff --git a/components/script/dom/paintworkletglobalscope.rs b/components/script/dom/paintworkletglobalscope.rs
index daee955baab..4287b347a83 100644
--- a/components/script/dom/paintworkletglobalscope.rs
+++ b/components/script/dom/paintworkletglobalscope.rs
@@ -10,6 +10,7 @@ use std::sync::{Arc, Mutex};
 use std::thread;
 use std::time::Duration;
 
+use base::id::PipelineId;
 use crossbeam_channel::{unbounded, Sender};
 use dom_struct::dom_struct;
 use euclid::{Scale, Size2D};
@@ -20,7 +21,6 @@ use js::jsapi::{
 use js::jsval::{JSVal, ObjectValue, UndefinedValue};
 use js::rust::wrappers::{Call, Construct1};
 use js::rust::{HandleValue, Runtime};
-use msg::constellation_msg::PipelineId;
 use net_traits::image_cache::ImageCache;
 use pixels::PixelFormat;
 use profile_traits::ipc;
diff --git a/components/script/dom/serviceworker.rs b/components/script/dom/serviceworker.rs
index ee318f9a111..02f7b60f4c0 100644
--- a/components/script/dom/serviceworker.rs
+++ b/components/script/dom/serviceworker.rs
@@ -4,10 +4,10 @@
 
 use std::cell::Cell;
 
+use base::id::ServiceWorkerId;
 use dom_struct::dom_struct;
 use js::jsapi::{Heap, JSObject};
 use js::rust::{CustomAutoRooter, CustomAutoRooterGuard, HandleValue};
-use msg::constellation_msg::ServiceWorkerId;
 use script_traits::{DOMMessage, ScriptMsg};
 use servo_url::ServoUrl;
 
diff --git a/components/script/dom/serviceworkerglobalscope.rs b/components/script/dom/serviceworkerglobalscope.rs
index 8bede70297e..bd2c6dc79d0 100644
--- a/components/script/dom/serviceworkerglobalscope.rs
+++ b/components/script/dom/serviceworkerglobalscope.rs
@@ -7,6 +7,7 @@ use std::sync::Arc;
 use std::thread::{self, JoinHandle};
 use std::time::{Duration, Instant};
 
+use base::id::PipelineId;
 use crossbeam_channel::{after, unbounded, Receiver, Sender};
 use devtools_traits::DevtoolScriptControlMsg;
 use dom_struct::dom_struct;
@@ -14,7 +15,6 @@ use ipc_channel::ipc::{IpcReceiver, IpcSender};
 use ipc_channel::router::ROUTER;
 use js::jsapi::{JSContext, JS_AddInterruptCallback};
 use js::jsval::UndefinedValue;
-use msg::constellation_msg::PipelineId;
 use net_traits::request::{CredentialsMode, Destination, ParserMetadata, Referrer, RequestBuilder};
 use net_traits::{CustomResponseMediator, IpcSend};
 use parking_lot::Mutex;
diff --git a/components/script/dom/serviceworkerregistration.rs b/components/script/dom/serviceworkerregistration.rs
index 481ff3aa965..c1eb63fa648 100644
--- a/components/script/dom/serviceworkerregistration.rs
+++ b/components/script/dom/serviceworkerregistration.rs
@@ -4,9 +4,9 @@
 
 use std::cell::Cell;
 
+use base::id::ServiceWorkerRegistrationId;
 use devtools_traits::WorkerId;
 use dom_struct::dom_struct;
-use msg::constellation_msg::ServiceWorkerRegistrationId;
 use script_traits::{ScopeThings, WorkerScriptLoadOrigin};
 use servo_url::ServoUrl;
 use uuid::Uuid;
diff --git a/components/script/dom/servoparser/mod.rs b/components/script/dom/servoparser/mod.rs
index 507e2a2cb99..138aa8d4546 100644
--- a/components/script/dom/servoparser/mod.rs
+++ b/components/script/dom/servoparser/mod.rs
@@ -6,6 +6,7 @@ use std::borrow::Cow;
 use std::cell::Cell;
 use std::mem;
 
+use base::id::PipelineId;
 use base64::engine::general_purpose;
 use base64::Engine as _;
 use content_security_policy::{self as csp, CspList};
@@ -20,7 +21,6 @@ use html5ever::tree_builder::{ElementFlags, NextParserState, NodeOrText, QuirksM
 use html5ever::{local_name, namespace_url, ns, Attribute, ExpandedName, LocalName, QualName};
 use hyper_serde::Serde;
 use mime::{self, Mime};
-use msg::constellation_msg::PipelineId;
 use net_traits::{
     FetchMetadata, FetchResponseListener, Metadata, NetworkError, ResourceFetchTiming,
     ResourceTimingType,
diff --git a/components/script/dom/servoparser/prefetch.rs b/components/script/dom/servoparser/prefetch.rs
index d11da362149..1f57ccc0a94 100644
--- a/components/script/dom/servoparser/prefetch.rs
+++ b/components/script/dom/servoparser/prefetch.rs
@@ -2,6 +2,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
+use base::id::PipelineId;
 use html5ever::buffer_queue::BufferQueue;
 use html5ever::tokenizer::states::RawKind;
 use html5ever::tokenizer::{
@@ -9,7 +10,6 @@ use html5ever::tokenizer::{
 };
 use html5ever::{local_name, Attribute, LocalName};
 use js::jsapi::JSTracer;
-use msg::constellation_msg::PipelineId;
 use net_traits::request::{CorsSettings, CredentialsMode, ParserMetadata, Referrer};
 use net_traits::{CoreResourceMsg, FetchChannels, IpcSend, ReferrerPolicy, ResourceThreads};
 use servo_url::{ImmutableOrigin, ServoUrl};
diff --git a/components/script/dom/testworkletglobalscope.rs b/components/script/dom/testworkletglobalscope.rs
index 71c20ad9966..2540bc31415 100644
--- a/components/script/dom/testworkletglobalscope.rs
+++ b/components/script/dom/testworkletglobalscope.rs
@@ -4,10 +4,10 @@
 
 use std::collections::HashMap;
 
+use base::id::PipelineId;
 use crossbeam_channel::Sender;
 use dom_struct::dom_struct;
 use js::rust::Runtime;
-use msg::constellation_msg::PipelineId;
 use servo_url::ServoUrl;
 
 use crate::dom::bindings::cell::DomRefCell;
diff --git a/components/script/dom/window.rs b/components/script/dom/window.rs
index ae50518c2c8..b034c9c5d29 100644
--- a/components/script/dom/window.rs
+++ b/components/script/dom/window.rs
@@ -16,6 +16,7 @@ use std::{cmp, env, mem};
 
 use app_units::Au;
 use backtrace::Backtrace;
+use base::id::{BrowsingContextId, PipelineId};
 use base64::Engine;
 use bluetooth_traits::BluetoothRequest;
 use canvas_traits::webgl::WebGLChan;
@@ -26,7 +27,6 @@ use dom_struct::dom_struct;
 use embedder_traits::{EmbedderMsg, PromptDefinition, PromptOrigin, PromptResult};
 use euclid::default::{Point2D as UntypedPoint2D, Rect as UntypedRect};
 use euclid::{Point2D, Rect, Scale, Size2D, Vector2D};
-use gfx_traits::combine_id_with_fragment_type;
 use ipc_channel::ipc::{self, IpcSender};
 use ipc_channel::router::ROUTER;
 use js::conversions::ToJSValConvertible;
@@ -38,7 +38,6 @@ use js::rust::{
 };
 use malloc_size_of::MallocSizeOf;
 use media::WindowGLContext;
-use msg::constellation_msg::{BrowsingContextId, PipelineId};
 use net_traits::image_cache::{
     ImageCache, ImageResponder, ImageResponse, PendingImageId, PendingImageResponse,
 };
@@ -50,7 +49,8 @@ use profile_traits::ipc as ProfiledIpc;
 use profile_traits::mem::ProfilerChan as MemProfilerChan;
 use profile_traits::time::ProfilerChan as TimeProfilerChan;
 use script_layout_interface::{
-    Layout, PendingImageState, QueryMsg, Reflow, ReflowGoal, ScriptReflow, TrustedNodeAddress,
+    combine_id_with_fragment_type, FragmentType, Layout, PendingImageState, QueryMsg, Reflow,
+    ReflowGoal, ScriptReflow, TrustedNodeAddress,
 };
 use script_traits::webdriver_msg::{WebDriverJSError, WebDriverJSResult};
 use script_traits::{
@@ -2110,10 +2110,7 @@ impl Window {
             .borrow_mut()
             .insert(node.to_opaque(), Vector2D::new(x_ as f32, y_ as f32));
         let scroll_id = ExternalScrollId(
-            combine_id_with_fragment_type(
-                node.to_opaque().id(),
-                gfx_traits::FragmentType::FragmentBody,
-            ),
+            combine_id_with_fragment_type(node.to_opaque().id(), FragmentType::FragmentBody),
             self.pipeline_id().into(),
         );
 
diff --git a/components/script/dom/windowproxy.rs b/components/script/dom/windowproxy.rs
index 24a7afe7672..92ecd52968d 100644
--- a/components/script/dom/windowproxy.rs
+++ b/components/script/dom/windowproxy.rs
@@ -5,6 +5,7 @@
 use std::cell::Cell;
 use std::ptr;
 
+use base::id::{BrowsingContextId, PipelineId, TopLevelBrowsingContextId};
 use dom_struct::dom_struct;
 use embedder_traits::EmbedderMsg;
 use html5ever::local_name;
@@ -27,7 +28,6 @@ use js::jsval::{JSVal, NullValue, PrivateValue, UndefinedValue};
 use js::rust::wrappers::{JS_TransplantObject, NewWindowProxy, SetWindowProxy};
 use js::rust::{get_object_class, Handle, MutableHandle};
 use js::JSCLASS_IS_GLOBAL;
-use msg::constellation_msg::{BrowsingContextId, PipelineId, TopLevelBrowsingContextId};
 use net_traits::request::Referrer;
 use script_traits::{
     AuxiliaryBrowsingContextLoadInfo, HistoryEntryReplacement, LoadData, LoadOrigin, NewLayoutInfo,
diff --git a/components/script/dom/workerglobalscope.rs b/components/script/dom/workerglobalscope.rs
index 7c10b459c93..61c5a4a59a7 100644
--- a/components/script/dom/workerglobalscope.rs
+++ b/components/script/dom/workerglobalscope.rs
@@ -7,6 +7,7 @@ use std::rc::Rc;
 use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::Arc;
 
+use base::id::{PipelineId, PipelineNamespace};
 use crossbeam_channel::Receiver;
 use devtools_traits::{DevtoolScriptControlMsg, WorkerId};
 use dom_struct::dom_struct;
@@ -14,7 +15,6 @@ use ipc_channel::ipc::IpcSender;
 use js::jsval::UndefinedValue;
 use js::panic::maybe_resume_unwind;
 use js::rust::{HandleValue, ParentRuntime};
-use msg::constellation_msg::{PipelineId, PipelineNamespace};
 use net_traits::request::{
     CredentialsMode, Destination, ParserMetadata, RequestBuilder as NetRequestInit,
 };
diff --git a/components/script/dom/worklet.rs b/components/script/dom/worklet.rs
index 318e4fc533b..697bba659e7 100644
--- a/components/script/dom/worklet.rs
+++ b/components/script/dom/worklet.rs
@@ -18,11 +18,11 @@ use std::sync::atomic::{AtomicIsize, Ordering};
 use std::sync::Arc;
 use std::thread;
 
+use base::id::PipelineId;
 use crossbeam_channel::{unbounded, Receiver, Sender};
 use dom_struct::dom_struct;
 use js::jsapi::{GCReason, JSGCParamKey, JSTracer, JS_GetGCParameter, JS_GC};
 use malloc_size_of::malloc_size_of_is_0;
-use msg::constellation_msg::PipelineId;
 use net_traits::request::{Destination, RequestBuilder, RequestMode};
 use net_traits::IpcSend;
 use servo_url::{ImmutableOrigin, ServoUrl};
diff --git a/components/script/dom/workletglobalscope.rs b/components/script/dom/workletglobalscope.rs
index f364926f71c..6357a896942 100644
--- a/components/script/dom/workletglobalscope.rs
+++ b/components/script/dom/workletglobalscope.rs
@@ -5,13 +5,13 @@
 use std::borrow::Cow;
 use std::sync::Arc;
 
+use base::id::PipelineId;
 use crossbeam_channel::Sender;
 use devtools_traits::ScriptToDevtoolsControlMsg;
 use dom_struct::dom_struct;
 use ipc_channel::ipc::IpcSender;
 use js::jsval::UndefinedValue;
 use js::rust::Runtime;
-use msg::constellation_msg::PipelineId;
 use net_traits::image_cache::ImageCache;
 use net_traits::ResourceThreads;
 use parking_lot::Mutex;
diff --git a/components/script/dom/xrsystem.rs b/components/script/dom/xrsystem.rs
index e7118d3544a..fdeb931b1d7 100644
--- a/components/script/dom/xrsystem.rs
+++ b/components/script/dom/xrsystem.rs
@@ -5,10 +5,10 @@
 use std::cell::Cell;
 use std::rc::Rc;
 
+use base::id::PipelineId;
 use dom_struct::dom_struct;
 use ipc_channel::ipc::{self as ipc_crate, IpcReceiver};
 use ipc_channel::router::ROUTER;
-use msg::constellation_msg::PipelineId;
 use profile_traits::ipc;
 use servo_config::pref;
 use webxr_api::{Error as XRError, Frame, Session, SessionInit, SessionMode};
diff --git a/components/script/layout_dom/node.rs b/components/script/layout_dom/node.rs
index 0cbdba64573..7a521d36220 100644
--- a/components/script/layout_dom/node.rs
+++ b/components/script/layout_dom/node.rs
@@ -8,9 +8,9 @@ use std::borrow::Cow;
 use std::fmt;
 use std::sync::Arc as StdArc;
 
+use base::id::{BrowsingContextId, PipelineId};
 use gfx_traits::ByteIndex;
 use html5ever::{local_name, namespace_url, ns};
-use msg::constellation_msg::{BrowsingContextId, PipelineId};
 use net_traits::image::base::{Image, ImageMetadata};
 use range::Range;
 use script_layout_interface::wrapper_traits::{
diff --git a/components/script/microtask.rs b/components/script/microtask.rs
index 904925fc9db..820afcc5f97 100644
--- a/components/script/microtask.rs
+++ b/components/script/microtask.rs
@@ -10,8 +10,8 @@ use std::cell::Cell;
 use std::mem;
 use std::rc::Rc;
 
+use base::id::PipelineId;
 use js::jsapi::{JSAutoRealm, JobQueueIsEmpty, JobQueueMayNotBeEmpty};
-use msg::constellation_msg::PipelineId;
 
 use crate::dom::bindings::callback::ExceptionHandling;
 use crate::dom::bindings::cell::DomRefCell;
diff --git a/components/script/script_runtime.rs b/components/script/script_runtime.rs
index 9aac9fb9baa..f635bd0b1a7 100644
--- a/components/script/script_runtime.rs
+++ b/components/script/script_runtime.rs
@@ -18,6 +18,7 @@ use std::sync::{Arc, Mutex};
 use std::time::{Duration, Instant};
 use std::{fmt, os, ptr, thread};
 
+use base::id::PipelineId;
 use js::glue::{
     CollectServoSizes, CreateJobQueue, DeleteJobQueue, DispatchableRun, JobQueueTraps,
     RUST_js_GetErrorMessage, SetBuildId, StreamConsumerConsumeChunk,
@@ -45,7 +46,6 @@ use js::rust::{
 };
 use lazy_static::lazy_static;
 use malloc_size_of::MallocSizeOfOps;
-use msg::constellation_msg::PipelineId;
 use profile_traits::mem::{Report, ReportKind, ReportsChan};
 use profile_traits::path;
 use servo_config::{opts, pref};
diff --git a/components/script/script_thread.rs b/components/script/script_thread.rs
index 1259d7f703e..7231dfc54dd 100644
--- a/components/script/script_thread.rs
+++ b/components/script/script_thread.rs
@@ -29,6 +29,13 @@ use std::sync::Arc;
 use std::time::{Duration, Instant, SystemTime, UNIX_EPOCH};
 use std::{ptr, thread};
 
+use background_hang_monitor_api::{
+    BackgroundHangMonitor, BackgroundHangMonitorExitSignal, HangAnnotation, MonitoredComponentId,
+    MonitoredComponentType, ScriptHangAnnotation,
+};
+use base::id::{
+    BrowsingContextId, HistoryStateId, PipelineId, PipelineNamespace, TopLevelBrowsingContextId,
+};
 use bluetooth_traits::BluetoothRequest;
 use canvas_traits::webgl::WebGLPipeline;
 use chrono::{DateTime, Local};
@@ -55,11 +62,6 @@ use js::rust::ParentRuntime;
 use media::WindowGLContext;
 use metrics::{PaintTimeMetrics, MAX_TASK_NS};
 use mime::{self, Mime};
-use msg::constellation_msg::{
-    BackgroundHangMonitor, BackgroundHangMonitorExitSignal, BrowsingContextId, HangAnnotation,
-    HistoryStateId, MonitoredComponentId, MonitoredComponentType, PipelineId, PipelineNamespace,
-    ScriptHangAnnotation, TopLevelBrowsingContextId,
-};
 use net_traits::image_cache::{ImageCache, PendingImageResponse};
 use net_traits::request::{CredentialsMode, Destination, RedirectMode, RequestBuilder};
 use net_traits::storage_thread::StorageType;
diff --git a/components/script/serviceworker_manager.rs b/components/script/serviceworker_manager.rs
index c16c5597b90..8059e4ee41b 100644
--- a/components/script/serviceworker_manager.rs
+++ b/components/script/serviceworker_manager.rs
@@ -12,10 +12,10 @@ use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::Arc;
 use std::thread::{self, JoinHandle};
 
+use base::id::{PipelineNamespace, ServiceWorkerId, ServiceWorkerRegistrationId};
 use crossbeam_channel::{select, unbounded, Receiver, RecvError, Sender};
 use ipc_channel::ipc::{self, IpcSender};
 use ipc_channel::router::ROUTER;
-use msg::constellation_msg::{PipelineNamespace, ServiceWorkerId, ServiceWorkerRegistrationId};
 use net_traits::{CoreResourceMsg, CustomResponseMediator};
 use script_traits::{
     DOMMessage, Job, JobError, JobResult, JobResultValue, JobType, SWManagerMsg, SWManagerSenders,
diff --git a/components/script/stylesheet_loader.rs b/components/script/stylesheet_loader.rs
index d9c2d789119..90aeb8754f1 100644
--- a/components/script/stylesheet_loader.rs
+++ b/components/script/stylesheet_loader.rs
@@ -5,12 +5,12 @@
 use std::sync::atomic::AtomicBool;
 use std::sync::Mutex;
 
+use base::id::PipelineId;
 use cssparser::SourceLocation;
 use encoding_rs::UTF_8;
 use ipc_channel::ipc;
 use ipc_channel::router::ROUTER;
 use mime::{self, Mime};
-use msg::constellation_msg::PipelineId;
 use net_traits::request::{CorsSettings, Destination, Referrer, RequestBuilder};
 use net_traits::{
     FetchMetadata, FetchResponseListener, FilteredMetadata, Metadata, NetworkError, ReferrerPolicy,
diff --git a/components/script/task_queue.rs b/components/script/task_queue.rs
index 0a84feae7b8..96fc49c81af 100644
--- a/components/script/task_queue.rs
+++ b/components/script/task_queue.rs
@@ -8,8 +8,8 @@ use std::cell::Cell;
 use std::collections::{HashMap, HashSet, VecDeque};
 use std::default::Default;
 
+use base::id::PipelineId;
 use crossbeam_channel::{self, Receiver, Sender};
-use msg::constellation_msg::PipelineId;
 
 use crate::dom::bindings::cell::DomRefCell;
 use crate::dom::worker::TrustedWorkerAddress;
diff --git a/components/script/task_source/dom_manipulation.rs b/components/script/task_source/dom_manipulation.rs
index eaff254a5cf..1469db66155 100644
--- a/components/script/task_source/dom_manipulation.rs
+++ b/components/script/task_source/dom_manipulation.rs
@@ -5,7 +5,7 @@
 use std::fmt;
 use std::result::Result;
 
-use msg::constellation_msg::PipelineId;
+use base::id::PipelineId;
 use servo_atoms::Atom;
 
 use crate::dom::bindings::inheritance::Castable;
diff --git a/components/script/task_source/file_reading.rs b/components/script/task_source/file_reading.rs
index 77e566dbf63..afb1f5c104a 100644
--- a/components/script/task_source/file_reading.rs
+++ b/components/script/task_source/file_reading.rs
@@ -2,7 +2,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
-use msg::constellation_msg::PipelineId;
+use base::id::PipelineId;
 
 use crate::dom::domexception::DOMErrorName;
 use crate::dom::filereader::{FileReader, GenerationId, ReadMetaData, TrustedFileReader};
diff --git a/components/script/task_source/gamepad.rs b/components/script/task_source/gamepad.rs
index e6694f3daea..9d38257bace 100644
--- a/components/script/task_source/gamepad.rs
+++ b/components/script/task_source/gamepad.rs
@@ -5,7 +5,7 @@
 use std::fmt;
 use std::result::Result;
 
-use msg::constellation_msg::PipelineId;
+use base::id::PipelineId;
 
 use crate::script_runtime::{CommonScriptMsg, ScriptChan, ScriptThreadEventCategory};
 use crate::task::{TaskCanceller, TaskOnce};
diff --git a/components/script/task_source/history_traversal.rs b/components/script/task_source/history_traversal.rs
index 1676461fa99..4bb90a1ffcb 100644
--- a/components/script/task_source/history_traversal.rs
+++ b/components/script/task_source/history_traversal.rs
@@ -2,8 +2,8 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
+use base::id::PipelineId;
 use crossbeam_channel::Sender;
-use msg::constellation_msg::PipelineId;
 
 use crate::script_runtime::{CommonScriptMsg, ScriptThreadEventCategory};
 use crate::script_thread::MainThreadScriptMsg;
diff --git a/components/script/task_source/media_element.rs b/components/script/task_source/media_element.rs
index 64d2f6c2764..944ffc4f5bf 100644
--- a/components/script/task_source/media_element.rs
+++ b/components/script/task_source/media_element.rs
@@ -5,8 +5,8 @@
 use std::fmt;
 use std::result::Result;
 
+use base::id::PipelineId;
 use crossbeam_channel::Sender;
-use msg::constellation_msg::PipelineId;
 use servo_atoms::Atom;
 
 use crate::dom::bindings::inheritance::Castable;
diff --git a/components/script/task_source/networking.rs b/components/script/task_source/networking.rs
index b55331af526..f142c1f6ae0 100644
--- a/components/script/task_source/networking.rs
+++ b/components/script/task_source/networking.rs
@@ -2,7 +2,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
-use msg::constellation_msg::PipelineId;
+use base::id::PipelineId;
 
 use crate::script_runtime::{CommonScriptMsg, ScriptChan, ScriptThreadEventCategory};
 use crate::task::{TaskCanceller, TaskOnce};
diff --git a/components/script/task_source/performance_timeline.rs b/components/script/task_source/performance_timeline.rs
index 9f6f56a2cf4..9bcfe4bc1d8 100644
--- a/components/script/task_source/performance_timeline.rs
+++ b/components/script/task_source/performance_timeline.rs
@@ -9,7 +9,7 @@
 use std::fmt;
 use std::result::Result;
 
-use msg::constellation_msg::PipelineId;
+use base::id::PipelineId;
 
 use crate::dom::bindings::refcounted::Trusted;
 use crate::dom::globalscope::GlobalScope;
diff --git a/components/script/task_source/port_message.rs b/components/script/task_source/port_message.rs
index b9bca1e6194..0ca613c647c 100644
--- a/components/script/task_source/port_message.rs
+++ b/components/script/task_source/port_message.rs
@@ -4,7 +4,7 @@
 
 use std::fmt;
 
-use msg::constellation_msg::PipelineId;
+use base::id::PipelineId;
 
 use crate::script_runtime::{CommonScriptMsg, ScriptChan, ScriptThreadEventCategory};
 use crate::task::{TaskCanceller, TaskOnce};
diff --git a/components/script/task_source/remote_event.rs b/components/script/task_source/remote_event.rs
index cadba9b3016..9a70d2a0234 100644
--- a/components/script/task_source/remote_event.rs
+++ b/components/script/task_source/remote_event.rs
@@ -2,7 +2,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
-use msg::constellation_msg::PipelineId;
+use base::id::PipelineId;
 
 use crate::script_runtime::{CommonScriptMsg, ScriptChan, ScriptThreadEventCategory};
 use crate::task::{TaskCanceller, TaskOnce};
diff --git a/components/script/task_source/rendering.rs b/components/script/task_source/rendering.rs
index 732eb2aef2b..43afa4abb68 100644
--- a/components/script/task_source/rendering.rs
+++ b/components/script/task_source/rendering.rs
@@ -5,7 +5,7 @@
 use std::fmt;
 use std::result::Result;
 
-use msg::constellation_msg::PipelineId;
+use base::id::PipelineId;
 
 use crate::script_runtime::{CommonScriptMsg, ScriptChan, ScriptThreadEventCategory};
 use crate::task::{TaskCanceller, TaskOnce};
diff --git a/components/script/task_source/timer.rs b/components/script/task_source/timer.rs
index e565a3aaa22..4f8ad10d811 100644
--- a/components/script/task_source/timer.rs
+++ b/components/script/task_source/timer.rs
@@ -4,7 +4,7 @@
 
 use std::fmt;
 
-use msg::constellation_msg::PipelineId;
+use base::id::PipelineId;
 
 use crate::script_runtime::{CommonScriptMsg, ScriptChan, ScriptThreadEventCategory};
 use crate::task::{TaskCanceller, TaskOnce};
diff --git a/components/script/task_source/user_interaction.rs b/components/script/task_source/user_interaction.rs
index a16277f2781..9ddc06d9185 100644
--- a/components/script/task_source/user_interaction.rs
+++ b/components/script/task_source/user_interaction.rs
@@ -5,8 +5,8 @@
 use std::fmt;
 use std::result::Result;
 
+use base::id::PipelineId;
 use crossbeam_channel::Sender;
-use msg::constellation_msg::PipelineId;
 use servo_atoms::Atom;
 
 use crate::dom::bindings::inheritance::Castable;
diff --git a/components/script/task_source/websocket.rs b/components/script/task_source/websocket.rs
index 27ad5202373..2d05067e28b 100644
--- a/components/script/task_source/websocket.rs
+++ b/components/script/task_source/websocket.rs
@@ -2,7 +2,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
-use msg::constellation_msg::PipelineId;
+use base::id::PipelineId;
 
 use crate::script_runtime::{CommonScriptMsg, ScriptChan, ScriptThreadEventCategory};
 use crate::task::{TaskCanceller, TaskOnce};
diff --git a/components/script/webdriver_handlers.rs b/components/script/webdriver_handlers.rs
index ebc15484e92..11c43f40878 100644
--- a/components/script/webdriver_handlers.rs
+++ b/components/script/webdriver_handlers.rs
@@ -6,6 +6,7 @@ use std::cmp;
 use std::collections::HashMap;
 use std::ffi::CString;
 
+use base::id::{BrowsingContextId, PipelineId};
 use cookie::Cookie;
 use euclid::default::{Point2D, Rect, Size2D};
 use hyper_serde::Serde;
@@ -14,7 +15,6 @@ use js::jsapi::{HandleValueArray, JSAutoRealm, JSContext, JSType, JS_IsException
 use js::jsval::UndefinedValue;
 use js::rust::wrappers::{JS_CallFunctionName, JS_GetProperty, JS_HasOwnProperty, JS_TypeOfValue};
 use js::rust::{HandleObject, HandleValue};
-use msg::constellation_msg::{BrowsingContextId, PipelineId};
 use net_traits::CookieSource::{NonHTTP, HTTP};
 use net_traits::CoreResourceMsg::{DeleteCookies, GetCookiesDataForUrl, SetCookieForUrl};
 use net_traits::IpcSend;
diff --git a/components/servo/Cargo.toml b/components/servo/Cargo.toml
index c0f3555b1c2..18181c40e30 100644
--- a/components/servo/Cargo.toml
+++ b/components/servo/Cargo.toml
@@ -34,6 +34,7 @@ xr-profile = ["canvas/xr-profile", "canvas_traits/xr-profile", "script/xr-profil
 
 [dependencies]
 background_hang_monitor = { path = "../background_hang_monitor" }
+base = { workspace = true }
 bluetooth = { path = "../bluetooth" }
 bluetooth_traits = { workspace = true }
 canvas = { path = "../canvas", default-features = false }
@@ -58,7 +59,6 @@ layout_thread_2020 = { path = "../layout_thread_2020" }
 log = { workspace = true }
 media = { path = "../media" }
 mozangle = { workspace = true }
-msg = { workspace = true }
 net = { path = "../net" }
 net_traits = { workspace = true }
 profile = { path = "../profile" }
diff --git a/components/servo/lib.rs b/components/servo/lib.rs
index 17b3541ee52..fc15c830100 100644
--- a/components/servo/lib.rs
+++ b/components/servo/lib.rs
@@ -25,6 +25,8 @@ use std::rc::Rc;
 use std::sync::{Arc, Mutex};
 use std::vec::Drain;
 
+pub use base::id::TopLevelBrowsingContextId;
+use base::id::{PipelineNamespace, PipelineNamespaceId};
 use bluetooth::BluetoothThreadFactory;
 use bluetooth_traits::BluetoothRequest;
 use canvas::canvas_paint_thread::{self, CanvasPaintThread};
@@ -70,8 +72,6 @@ pub use gleam::gl;
 use ipc_channel::ipc::{self, IpcSender};
 use log::{error, trace, warn, Log, Metadata, Record};
 use media::{GLPlayerThreads, GlApi, NativeDisplay, WindowGLContext};
-pub use msg::constellation_msg::TopLevelBrowsingContextId;
-use msg::constellation_msg::{PipelineNamespace, PipelineNamespaceId};
 use net::resource_thread::new_resource_threads;
 use net_traits::IpcSend;
 use profile::{mem as profile_mem, time as profile_time};
@@ -96,12 +96,13 @@ use webrender_api::{
     NativeFontHandle,
 };
 use webrender_traits::{
-    WebrenderExternalImageHandlers, WebrenderExternalImageRegistry, WebrenderImageHandlerType,
+    WebRenderFontApi, WebrenderExternalImageHandlers, WebrenderExternalImageRegistry,
+    WebrenderImageHandlerType,
 };
 pub use {
-    background_hang_monitor, bluetooth, bluetooth_traits, canvas, canvas_traits, compositing,
+    background_hang_monitor, base, bluetooth, bluetooth_traits, canvas, canvas_traits, compositing,
     constellation, devtools, devtools_traits, embedder_traits, euclid, gfx, ipc_channel,
-    keyboard_types, layout_thread_2013, layout_thread_2020, media, msg, net, net_traits, profile,
+    keyboard_types, layout_thread_2013, layout_thread_2020, media, net, net_traits, profile,
     profile_traits, script, script_layout_interface, script_traits, servo_config as config,
     servo_config, servo_geometry, servo_url as url, servo_url, style, style_traits, webgpu,
     webrender_api, webrender_traits,
@@ -1051,7 +1052,7 @@ fn create_constellation(
 
 struct FontCacheWR(CompositorProxy);
 
-impl gfx_traits::WebrenderApi for FontCacheWR {
+impl WebRenderFontApi for FontCacheWR {
     fn add_font_instance(
         &self,
         font_key: FontKey,
diff --git a/components/shared/background_hang_monitor/Cargo.toml b/components/shared/background_hang_monitor/Cargo.toml
new file mode 100644
index 00000000000..c8d0685a377
--- /dev/null
+++ b/components/shared/background_hang_monitor/Cargo.toml
@@ -0,0 +1,24 @@
+[package]
+name = "background_hang_monitor_api"
+version = "0.0.1"
+authors = ["The Servo Project Developers"]
+license = "MPL-2.0"
+edition = "2018"
+publish = false
+
+[lib]
+name = "background_hang_monitor_api"
+path = "lib.rs"
+test = false
+doctest = false
+
+[dependencies]
+base = { workspace = true }
+ipc-channel = { workspace = true }
+lazy_static = { workspace = true }
+malloc_size_of = { workspace = true }
+malloc_size_of_derive = { workspace = true }
+parking_lot = { workspace = true }
+serde = { workspace = true }
+size_of_test = { workspace = true }
+webrender_api = { workspace = true }
diff --git a/components/shared/background_hang_monitor/lib.rs b/components/shared/background_hang_monitor/lib.rs
new file mode 100644
index 00000000000..8fbec70f041
--- /dev/null
+++ b/components/shared/background_hang_monitor/lib.rs
@@ -0,0 +1,212 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+#![deny(unsafe_code)]
+
+//! An API interface to the BackgroundHangMonitor.
+
+use std::time::Duration;
+use std::{fmt, mem};
+
+use base::id::PipelineId;
+use ipc_channel::ipc::IpcSender;
+use serde::{Deserialize, Serialize};
+
+#[derive(Clone, Copy, Debug, Deserialize, Serialize)]
+/// The equivalent of script::script_runtime::ScriptEventCategory
+pub enum ScriptHangAnnotation {
+    AttachLayout,
+    ConstellationMsg,
+    DevtoolsMsg,
+    DocumentEvent,
+    DomEvent,
+    FileRead,
+    FormPlannedNavigation,
+    ImageCacheMsg,
+    InputEvent,
+    HistoryEvent,
+    NetworkEvent,
+    Resize,
+    ScriptEvent,
+    SetScrollState,
+    SetViewport,
+    StylesheetLoad,
+    TimerEvent,
+    UpdateReplacedElement,
+    WebSocketEvent,
+    WorkerEvent,
+    WorkletEvent,
+    ServiceWorkerEvent,
+    EnterFullscreen,
+    ExitFullscreen,
+    WebVREvent,
+    PerformanceTimelineTask,
+    PortMessage,
+    WebGPUMsg,
+}
+
+#[derive(Clone, Copy, Debug, Deserialize, Serialize)]
+pub enum HangAnnotation {
+    Script(ScriptHangAnnotation),
+}
+
+/// Hang-alerts are sent by the monitor to the constellation.
+#[derive(Deserialize, Serialize)]
+pub enum HangMonitorAlert {
+    /// A component hang has been detected.
+    Hang(HangAlert),
+    /// Report a completed sampled profile.
+    Profile(Vec<u8>),
+}
+
+impl fmt::Debug for HangMonitorAlert {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        match *self {
+            HangMonitorAlert::Hang(..) => write!(fmt, "Hang"),
+            HangMonitorAlert::Profile(..) => write!(fmt, "Profile"),
+        }
+    }
+}
+
+/// Hang-alerts are sent by the monitor to the constellation.
+#[derive(Deserialize, Serialize)]
+pub enum HangAlert {
+    /// Report a transient hang.
+    Transient(MonitoredComponentId, HangAnnotation),
+    /// Report a permanent hang.
+    Permanent(MonitoredComponentId, HangAnnotation, Option<HangProfile>),
+}
+
+impl fmt::Debug for HangAlert {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        let (annotation, profile) = match self {
+            HangAlert::Transient(component_id, annotation) => {
+                write!(
+                    fmt,
+                    "\n The following component is experiencing a transient hang: \n {:?}",
+                    component_id
+                )?;
+                (*annotation, None)
+            },
+            HangAlert::Permanent(component_id, annotation, profile) => {
+                write!(
+                    fmt,
+                    "\n The following component is experiencing a permanent hang: \n {:?}",
+                    component_id
+                )?;
+                (*annotation, profile.clone())
+            },
+        };
+
+        write!(fmt, "\n Annotation for the hang:\n{:?}", annotation)?;
+        if let Some(profile) = profile {
+            write!(fmt, "\n {:?}", profile)?;
+        }
+
+        Ok(())
+    }
+}
+
+#[derive(Clone, Deserialize, Serialize)]
+pub struct HangProfileSymbol {
+    pub name: Option<String>,
+    pub filename: Option<String>,
+    pub lineno: Option<u32>,
+}
+
+#[derive(Clone, Deserialize, Serialize)]
+/// Info related to the activity of an hanging component.
+pub struct HangProfile {
+    pub backtrace: Vec<HangProfileSymbol>,
+}
+
+impl fmt::Debug for HangProfile {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        let hex_width = mem::size_of::<usize>() * 2 + 2;
+
+        write!(fmt, "HangProfile backtrace:")?;
+
+        if self.backtrace.is_empty() {
+            write!(fmt, "backtrace failed to resolve")?;
+            return Ok(());
+        }
+
+        for symbol in self.backtrace.iter() {
+            write!(fmt, "\n      {:1$}", "", hex_width)?;
+
+            if let Some(ref name) = symbol.name {
+                write!(fmt, " - {}", name)?;
+            } else {
+                write!(fmt, " - <unknown>")?;
+            }
+
+            if let (Some(ref file), Some(ref line)) = (symbol.filename.as_ref(), symbol.lineno) {
+                write!(fmt, "\n      {:3$}at {}:{}", "", file, line, hex_width)?;
+            }
+        }
+
+        Ok(())
+    }
+}
+
+#[derive(Clone, Debug, Deserialize, Eq, Hash, PartialEq, Serialize)]
+pub enum MonitoredComponentType {
+    Script,
+}
+
+#[derive(Clone, Debug, Deserialize, Eq, Hash, PartialEq, Serialize)]
+pub struct MonitoredComponentId(pub PipelineId, pub MonitoredComponentType);
+
+/// A handle to register components for hang monitoring,
+/// and to receive a means to communicate with the underlying hang monitor worker.
+pub trait BackgroundHangMonitorRegister: BackgroundHangMonitorClone + Send {
+    /// Register a component for hang monitoring:
+    /// to be called from within the thread to be monitored for hangs.
+    fn register_component(
+        &self,
+        component: MonitoredComponentId,
+        transient_hang_timeout: Duration,
+        permanent_hang_timeout: Duration,
+        exit_signal: Option<Box<dyn BackgroundHangMonitorExitSignal>>,
+    ) -> Box<dyn BackgroundHangMonitor>;
+}
+
+impl Clone for Box<dyn BackgroundHangMonitorRegister> {
+    fn clone(&self) -> Box<dyn BackgroundHangMonitorRegister> {
+        self.clone_box()
+    }
+}
+
+pub trait BackgroundHangMonitorClone {
+    fn clone_box(&self) -> Box<dyn BackgroundHangMonitorRegister>;
+}
+
+/// Proxy methods to communicate with the background hang monitor
+pub trait BackgroundHangMonitor {
+    /// Notify the start of handling an event.
+    fn notify_activity(&self, annotation: HangAnnotation);
+    /// Notify the start of waiting for a new event to come in.
+    fn notify_wait(&self);
+    /// Unregister the component from monitor.
+    fn unregister(&self);
+}
+
+/// A means for the BHM to signal a monitored component to exit.
+/// Useful when the component is hanging, and cannot be notified via the usual way.
+/// The component should implement this in a way allowing for the signal to be received when hanging,
+/// if at all.
+pub trait BackgroundHangMonitorExitSignal: Send {
+    /// Called by the BHM, to notify the monitored component to exit.
+    fn signal_to_exit(&self);
+}
+
+/// Messages to control the sampling profiler.
+#[derive(Deserialize, Serialize)]
+pub enum BackgroundHangMonitorControlMsg {
+    /// Enable the sampler, with a given sampling rate and max total sampling duration.
+    EnableSampler(Duration, Duration),
+    DisableSampler,
+    /// Exit, and propagate the signal to monitored components.
+    Exit(IpcSender<()>),
+}
diff --git a/components/shared/msg/Cargo.toml b/components/shared/base/Cargo.toml
index 97abd671eef..10cb0939d8c 100644
--- a/components/shared/msg/Cargo.toml
+++ b/components/shared/base/Cargo.toml
@@ -1,5 +1,5 @@
 [package]
-name = "msg"
+name = "base"
 version = "0.0.1"
 authors = ["The Servo Project Developers"]
 license = "MPL-2.0"
@@ -7,7 +7,7 @@ edition = "2018"
 publish = false
 
 [lib]
-name = "msg"
+name = "base"
 path = "lib.rs"
 test = false
 doctest = false
diff --git a/components/shared/msg/constellation_msg.rs b/components/shared/base/id.rs
index 93c18790255..06f69547bb7 100644
--- a/components/shared/msg/constellation_msg.rs
+++ b/components/shared/base/id.rs
@@ -2,16 +2,14 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
-//! The high-level interface from script to constellation. Using this abstract interface helps
-//! reduce coupling between these two components.
+//! Namespaces and ids shared by many crates in Servo.
 
 #![allow(clippy::new_without_default)]
 
 use std::cell::Cell;
+use std::fmt;
 use std::num::NonZeroU32;
 use std::sync::Arc;
-use std::time::Duration;
-use std::{fmt, mem};
 
 use ipc_channel::ipc::{self, IpcReceiver, IpcSender};
 use lazy_static::lazy_static;
@@ -65,12 +63,6 @@ macro_rules! namespace_id {
     };
 }
 
-#[derive(Clone, Copy, Debug, Deserialize, Eq, Hash, PartialEq, Serialize)]
-pub enum TraversalDirection {
-    Forward(usize),
-    Back(usize),
-}
-
 #[derive(Debug, Deserialize, Serialize)]
 /// Request a pipeline-namespace id from the constellation.
 pub struct PipelineNamespaceRequest(pub IpcSender<PipelineNamespaceId>);
@@ -444,221 +436,3 @@ pub const TEST_BROWSING_CONTEXT_ID: BrowsingContextId = BrowsingContextId {
     namespace_id: TEST_NAMESPACE,
     index: TEST_BROWSING_CONTEXT_INDEX,
 };
-
-// Used to specify the kind of input method editor appropriate to edit a field.
-// This is a subset of htmlinputelement::InputType because some variants of InputType
-// don't make sense in this context.
-#[derive(Debug, Deserialize, Serialize)]
-pub enum InputMethodType {
-    Color,
-    Date,
-    DatetimeLocal,
-    Email,
-    Month,
-    Number,
-    Password,
-    Search,
-    Tel,
-    Text,
-    Time,
-    Url,
-    Week,
-}
-
-#[derive(Clone, Copy, Debug, Deserialize, Serialize)]
-/// The equivalent of script::script_runtime::ScriptEventCategory
-pub enum ScriptHangAnnotation {
-    AttachLayout,
-    ConstellationMsg,
-    DevtoolsMsg,
-    DocumentEvent,
-    DomEvent,
-    FileRead,
-    FormPlannedNavigation,
-    ImageCacheMsg,
-    InputEvent,
-    HistoryEvent,
-    NetworkEvent,
-    Resize,
-    ScriptEvent,
-    SetScrollState,
-    SetViewport,
-    StylesheetLoad,
-    TimerEvent,
-    UpdateReplacedElement,
-    WebSocketEvent,
-    WorkerEvent,
-    WorkletEvent,
-    ServiceWorkerEvent,
-    EnterFullscreen,
-    ExitFullscreen,
-    WebVREvent,
-    PerformanceTimelineTask,
-    PortMessage,
-    WebGPUMsg,
-}
-
-#[derive(Clone, Copy, Debug, Deserialize, Serialize)]
-pub enum HangAnnotation {
-    Script(ScriptHangAnnotation),
-}
-
-/// Hang-alerts are sent by the monitor to the constellation.
-#[derive(Deserialize, Serialize)]
-pub enum HangMonitorAlert {
-    /// A component hang has been detected.
-    Hang(HangAlert),
-    /// Report a completed sampled profile.
-    Profile(Vec<u8>),
-}
-
-impl fmt::Debug for HangMonitorAlert {
-    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
-        match *self {
-            HangMonitorAlert::Hang(..) => write!(fmt, "Hang"),
-            HangMonitorAlert::Profile(..) => write!(fmt, "Profile"),
-        }
-    }
-}
-
-/// Hang-alerts are sent by the monitor to the constellation.
-#[derive(Deserialize, Serialize)]
-pub enum HangAlert {
-    /// Report a transient hang.
-    Transient(MonitoredComponentId, HangAnnotation),
-    /// Report a permanent hang.
-    Permanent(MonitoredComponentId, HangAnnotation, Option<HangProfile>),
-}
-
-impl fmt::Debug for HangAlert {
-    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
-        let (annotation, profile) = match self {
-            HangAlert::Transient(component_id, annotation) => {
-                write!(
-                    fmt,
-                    "\n The following component is experiencing a transient hang: \n {:?}",
-                    component_id
-                )?;
-                (*annotation, None)
-            },
-            HangAlert::Permanent(component_id, annotation, profile) => {
-                write!(
-                    fmt,
-                    "\n The following component is experiencing a permanent hang: \n {:?}",
-                    component_id
-                )?;
-                (*annotation, profile.clone())
-            },
-        };
-
-        write!(fmt, "\n Annotation for the hang:\n{:?}", annotation)?;
-        if let Some(profile) = profile {
-            write!(fmt, "\n {:?}", profile)?;
-        }
-
-        Ok(())
-    }
-}
-
-#[derive(Clone, Deserialize, Serialize)]
-pub struct HangProfileSymbol {
-    pub name: Option<String>,
-    pub filename: Option<String>,
-    pub lineno: Option<u32>,
-}
-
-#[derive(Clone, Deserialize, Serialize)]
-/// Info related to the activity of an hanging component.
-pub struct HangProfile {
-    pub backtrace: Vec<HangProfileSymbol>,
-}
-
-impl fmt::Debug for HangProfile {
-    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
-        let hex_width = mem::size_of::<usize>() * 2 + 2;
-
-        write!(fmt, "HangProfile backtrace:")?;
-
-        if self.backtrace.is_empty() {
-            write!(fmt, "backtrace failed to resolve")?;
-            return Ok(());
-        }
-
-        for symbol in self.backtrace.iter() {
-            write!(fmt, "\n      {:1$}", "", hex_width)?;
-
-            if let Some(ref name) = symbol.name {
-                write!(fmt, " - {}", name)?;
-            } else {
-                write!(fmt, " - <unknown>")?;
-            }
-
-            if let (Some(ref file), Some(ref line)) = (symbol.filename.as_ref(), symbol.lineno) {
-                write!(fmt, "\n      {:3$}at {}:{}", "", file, line, hex_width)?;
-            }
-        }
-
-        Ok(())
-    }
-}
-
-#[derive(Clone, Debug, Deserialize, Eq, Hash, PartialEq, Serialize)]
-pub enum MonitoredComponentType {
-    Script,
-}
-
-#[derive(Clone, Debug, Deserialize, Eq, Hash, PartialEq, Serialize)]
-pub struct MonitoredComponentId(pub PipelineId, pub MonitoredComponentType);
-
-/// A handle to register components for hang monitoring,
-/// and to receive a means to communicate with the underlying hang monitor worker.
-pub trait BackgroundHangMonitorRegister: BackgroundHangMonitorClone + Send {
-    /// Register a component for hang monitoring:
-    /// to be called from within the thread to be monitored for hangs.
-    fn register_component(
-        &self,
-        component: MonitoredComponentId,
-        transient_hang_timeout: Duration,
-        permanent_hang_timeout: Duration,
-        exit_signal: Option<Box<dyn BackgroundHangMonitorExitSignal>>,
-    ) -> Box<dyn BackgroundHangMonitor>;
-}
-
-impl Clone for Box<dyn BackgroundHangMonitorRegister> {
-    fn clone(&self) -> Box<dyn BackgroundHangMonitorRegister> {
-        self.clone_box()
-    }
-}
-
-pub trait BackgroundHangMonitorClone {
-    fn clone_box(&self) -> Box<dyn BackgroundHangMonitorRegister>;
-}
-
-/// Proxy methods to communicate with the background hang monitor
-pub trait BackgroundHangMonitor {
-    /// Notify the start of handling an event.
-    fn notify_activity(&self, annotation: HangAnnotation);
-    /// Notify the start of waiting for a new event to come in.
-    fn notify_wait(&self);
-    /// Unregister the component from monitor.
-    fn unregister(&self);
-}
-
-/// A means for the BHM to signal a monitored component to exit.
-/// Useful when the component is hanging, and cannot be notified via the usual way.
-/// The component should implement this in a way allowing for the signal to be received when hanging,
-/// if at all.
-pub trait BackgroundHangMonitorExitSignal: Send {
-    /// Called by the BHM, to notify the monitored component to exit.
-    fn signal_to_exit(&self);
-}
-
-/// Messages to control the sampling profiler.
-#[derive(Deserialize, Serialize)]
-pub enum BackgroundHangMonitorControlMsg {
-    /// Enable the sampler, with a given sampling rate and max total sampling duration.
-    EnableSampler(Duration, Duration),
-    DisableSampler,
-    /// Exit, and propagate the signal to monitored components.
-    Exit(IpcSender<()>),
-}
diff --git a/components/shared/base/lib.rs b/components/shared/base/lib.rs
new file mode 100644
index 00000000000..2057c9aa8c2
--- /dev/null
+++ b/components/shared/base/lib.rs
@@ -0,0 +1,45 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+#![deny(unsafe_code)]
+
+//! A crate to hold very common types in Servo.
+//!
+//! You should almost never need to add a data type to this crate. Instead look for
+//! a more shared crate that has fewer dependents.
+
+use serde::{Deserialize, Serialize};
+
+pub mod id;
+pub mod print_tree;
+use webrender_api::Epoch as WebRenderEpoch;
+
+/// A struct for denoting the age of messages; prevents race conditions.
+#[derive(Clone, Copy, Debug, Deserialize, Eq, Hash, Ord, PartialEq, PartialOrd, Serialize)]
+pub struct Epoch(pub u32);
+
+impl Epoch {
+    pub fn next(&mut self) {
+        self.0 += 1;
+    }
+}
+
+impl From<Epoch> for WebRenderEpoch {
+    fn from(val: Epoch) -> Self {
+        WebRenderEpoch(val.0)
+    }
+}
+
+pub trait WebRenderEpochToU16 {
+    fn as_u16(&self) -> u16;
+}
+
+impl WebRenderEpochToU16 for WebRenderEpoch {
+    /// The value of this [`Epoch`] as a u16 value. Note that if this Epoch's
+    /// value is more than u16::MAX, then the return value will be modulo
+    /// u16::MAX.
+    fn as_u16(&self) -> u16 {
+        (self.0 % u16::MAX as u32) as u16
+    }
+}
diff --git a/components/shared/gfx/print_tree.rs b/components/shared/base/print_tree.rs
index 03e47b21317..03e47b21317 100644
--- a/components/shared/gfx/print_tree.rs
+++ b/components/shared/base/print_tree.rs
diff --git a/components/shared/compositing/Cargo.toml b/components/shared/compositing/Cargo.toml
index b35e7560f3e..aed9a0e3565 100644
--- a/components/shared/compositing/Cargo.toml
+++ b/components/shared/compositing/Cargo.toml
@@ -11,6 +11,7 @@ name = "compositing_traits"
 path = "lib.rs"
 
 [dependencies]
+base = { workspace = true }
 canvas = { path = "../../canvas" }
 crossbeam-channel = { workspace = true }
 embedder_traits = { workspace = true }
@@ -19,7 +20,6 @@ gfx_traits = { workspace = true }
 ipc-channel = { workspace = true }
 keyboard-types = { workspace = true }
 log = { workspace = true }
-msg = { workspace = true }
 net_traits = { workspace = true }
 script_traits = { workspace = true }
 servo_url = { path = "../../url" }
diff --git a/components/shared/compositing/constellation_msg.rs b/components/shared/compositing/constellation_msg.rs
index 2a64db84651..2536a6cfc05 100644
--- a/components/shared/compositing/constellation_msg.rs
+++ b/components/shared/compositing/constellation_msg.rs
@@ -6,16 +6,14 @@ use std::collections::HashMap;
 use std::fmt;
 use std::time::Duration;
 
+use base::id::{BrowsingContextId, PipelineId, TopLevelBrowsingContextId, WebViewId};
+use base::Epoch;
 use embedder_traits::Cursor;
-use gfx_traits::Epoch;
 use ipc_channel::ipc::IpcSender;
 use keyboard_types::KeyboardEvent;
-use msg::constellation_msg::{
-    BrowsingContextId, PipelineId, TopLevelBrowsingContextId, TraversalDirection, WebViewId,
-};
 use script_traits::{
     AnimationTickType, CompositorEvent, GamepadEvent, LogEntry, MediaSessionActionType,
-    WebDriverCommandMsg, WindowSizeData, WindowSizeType,
+    TraversalDirection, WebDriverCommandMsg, WindowSizeData, WindowSizeType,
 };
 use servo_url::ServoUrl;
 
diff --git a/components/shared/compositing/lib.rs b/components/shared/compositing/lib.rs
index 21f77a4cae6..34c390cca85 100644
--- a/components/shared/compositing/lib.rs
+++ b/components/shared/compositing/lib.rs
@@ -8,15 +8,15 @@ mod constellation_msg;
 
 use std::fmt::{Debug, Error, Formatter};
 
+use base::id::{PipelineId, TopLevelBrowsingContextId};
+use base::Epoch;
 use canvas::canvas_paint_thread::ImageUpdate;
 pub use constellation_msg::ConstellationMsg;
 use crossbeam_channel::{Receiver, Sender};
 use embedder_traits::EventLoopWaker;
 use euclid::Rect;
-use gfx_traits::Epoch;
 use ipc_channel::ipc::IpcSender;
 use log::warn;
-use msg::constellation_msg::{PipelineId, TopLevelBrowsingContextId};
 use net_traits::image::base::Image;
 use net_traits::NetToCompositorMsg;
 use script_traits::{
diff --git a/components/shared/devtools/Cargo.toml b/components/shared/devtools/Cargo.toml
index c3be3bcb01b..d68e3bbb612 100644
--- a/components/shared/devtools/Cargo.toml
+++ b/components/shared/devtools/Cargo.toml
@@ -11,12 +11,12 @@ name = "devtools_traits"
 path = "lib.rs"
 
 [dependencies]
+base = { workspace = true }
 bitflags = { workspace = true }
 http = { workspace = true }
 ipc-channel = { workspace = true }
 malloc_size_of = { workspace = true }
 malloc_size_of_derive = { workspace = true }
-msg = { workspace = true }
 serde = { workspace = true }
 servo_url = { path = "../../url" }
 time = { workspace = true }
diff --git a/components/shared/devtools/lib.rs b/components/shared/devtools/lib.rs
index 0726bb48541..f690fb59e0d 100644
--- a/components/shared/devtools/lib.rs
+++ b/components/shared/devtools/lib.rs
@@ -14,11 +14,11 @@
 use std::net::TcpStream;
 use std::time::{Duration, SystemTime};
 
+use base::id::{BrowsingContextId, PipelineId};
 use bitflags::bitflags;
 use http::{HeaderMap, Method};
 use ipc_channel::ipc::IpcSender;
 use malloc_size_of_derive::MallocSizeOf;
-use msg::constellation_msg::{BrowsingContextId, PipelineId};
 use serde::{Deserialize, Serialize};
 use servo_url::ServoUrl;
 use uuid::Uuid;
diff --git a/components/shared/embedder/Cargo.toml b/components/shared/embedder/Cargo.toml
index c1d7456a156..f68e3b47d2c 100644
--- a/components/shared/embedder/Cargo.toml
+++ b/components/shared/embedder/Cargo.toml
@@ -11,13 +11,13 @@ name = "embedder_traits"
 path = "lib.rs"
 
 [dependencies]
+base = { workspace = true }
 cfg-if = { workspace = true }
 crossbeam-channel = { workspace = true }
 ipc-channel = { workspace = true }
 keyboard-types = { workspace = true }
 lazy_static = { workspace = true }
 log = { workspace = true }
-msg = { workspace = true }
 num-derive = "0.4"
 num-traits = { workspace = true }
 serde = { workspace = true }
diff --git a/components/shared/embedder/lib.rs b/components/shared/embedder/lib.rs
index 0acf7d01ce5..0a5cfdbb479 100644
--- a/components/shared/embedder/lib.rs
+++ b/components/shared/embedder/lib.rs
@@ -6,11 +6,11 @@ pub mod resources;
 
 use std::fmt::{Debug, Error, Formatter};
 
+use base::id::{PipelineId, TopLevelBrowsingContextId, WebViewId};
 use crossbeam_channel::{Receiver, Sender};
 use ipc_channel::ipc::IpcSender;
 use keyboard_types::KeyboardEvent;
 use log::warn;
-use msg::constellation_msg::{InputMethodType, PipelineId, TopLevelBrowsingContextId, WebViewId};
 use num_derive::FromPrimitive;
 use serde::{Deserialize, Serialize};
 use servo_url::ServoUrl;
@@ -368,3 +368,23 @@ pub enum PermissionRequest {
     Granted,
     Denied,
 }
+
+/// Used to specify the kind of input method editor appropriate to edit a field.
+/// This is a subset of htmlinputelement::InputType because some variants of InputType
+/// don't make sense in this context.
+#[derive(Debug, Deserialize, Serialize)]
+pub enum InputMethodType {
+    Color,
+    Date,
+    DatetimeLocal,
+    Email,
+    Month,
+    Number,
+    Password,
+    Search,
+    Tel,
+    Text,
+    Time,
+    Url,
+    Week,
+}
diff --git a/components/shared/gfx/lib.rs b/components/shared/gfx/lib.rs
index 2ae2d026fda..e5699f2504a 100644
--- a/components/shared/gfx/lib.rs
+++ b/components/shared/gfx/lib.rs
@@ -2,71 +2,11 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
-#![crate_name = "gfx_traits"]
-#![crate_type = "rlib"]
 #![deny(unsafe_code)]
 
-pub mod print_tree;
-
-use std::sync::atomic::{AtomicU64, Ordering};
-use std::sync::Arc;
-
 use malloc_size_of_derive::MallocSizeOf;
 use range::{int_range_index, RangeIndex};
 use serde::{Deserialize, Serialize};
-use webrender_api::{
-    Epoch as WebRenderEpoch, FontInstanceFlags, FontInstanceKey, FontKey, NativeFontHandle,
-};
-
-/// A newtype struct for denoting the age of messages; prevents race conditions.
-#[derive(Clone, Copy, Debug, Deserialize, Eq, Hash, Ord, PartialEq, PartialOrd, Serialize)]
-pub struct Epoch(pub u32);
-
-impl Epoch {
-    pub fn next(&mut self) {
-        self.0 += 1;
-    }
-}
-
-impl From<Epoch> for WebRenderEpoch {
-    fn from(val: Epoch) -> Self {
-        WebRenderEpoch(val.0)
-    }
-}
-
-pub trait WebRenderEpochToU16 {
-    fn as_u16(&self) -> u16;
-}
-
-impl WebRenderEpochToU16 for WebRenderEpoch {
-    /// The value of this [`Epoch`] as a u16 value. Note that if this Epoch's
-    /// value is more than u16::MAX, then the return value will be modulo
-    /// u16::MAX.
-    fn as_u16(&self) -> u16 {
-        (self.0 % u16::MAX as u32) as u16
-    }
-}
-
-/// A unique ID for every stacking context.
-#[derive(Clone, Copy, Debug, Deserialize, Eq, Hash, MallocSizeOf, PartialEq, Serialize)]
-pub struct StackingContextId(
-    /// The identifier for this StackingContext, derived from the Flow's memory address
-    /// and fragment type.  As a space optimization, these are combined into a single word.
-    pub u64,
-);
-
-impl StackingContextId {
-    /// Returns the stacking context ID for the outer document/layout root.
-    #[inline]
-    pub fn root() -> StackingContextId {
-        StackingContextId(0)
-    }
-
-    pub fn next(&self) -> StackingContextId {
-        let StackingContextId(id) = *self;
-        StackingContextId(id + 1)
-    }
-}
 
 int_range_index! {
     #[derive(Deserialize, MallocSizeOf, Serialize)]
@@ -74,61 +14,3 @@ int_range_index! {
     /// the middle of a glyph.
     struct ByteIndex(isize)
 }
-
-/// The type of fragment that a scroll root is created for.
-///
-/// This can only ever grow to maximum 4 entries. That's because we cram the value of this enum
-/// into the lower 2 bits of the `ScrollRootId`, which otherwise contains a 32-bit-aligned
-/// heap address.
-#[derive(Clone, Copy, Debug, Deserialize, Eq, Hash, MallocSizeOf, PartialEq, Serialize)]
-pub enum FragmentType {
-    /// A StackingContext for the fragment body itself.
-    FragmentBody,
-    /// A StackingContext created to contain ::before pseudo-element content.
-    BeforePseudoContent,
-    /// A StackingContext created to contain ::after pseudo-element content.
-    AfterPseudoContent,
-}
-
-/// The next ID that will be used for a special scroll root id.
-///
-/// A special scroll root is a scroll root that is created for generated content.
-static NEXT_SPECIAL_SCROLL_ROOT_ID: AtomicU64 = AtomicU64::new(0);
-
-/// If none of the bits outside this mask are set, the scroll root is a special scroll root.
-/// Note that we assume that the top 16 bits of the address space are unused on the platform.
-const SPECIAL_SCROLL_ROOT_ID_MASK: u64 = 0xffff;
-
-/// Returns a new scroll root ID for a scroll root.
-fn next_special_id() -> u64 {
-    // We shift this left by 2 to make room for the fragment type ID.
-    ((NEXT_SPECIAL_SCROLL_ROOT_ID.fetch_add(1, Ordering::SeqCst) + 1) << 2) &
-        SPECIAL_SCROLL_ROOT_ID_MASK
-}
-
-pub fn combine_id_with_fragment_type(id: usize, fragment_type: FragmentType) -> u64 {
-    debug_assert_eq!(id & (fragment_type as usize), 0);
-    if fragment_type == FragmentType::FragmentBody {
-        id as u64
-    } else {
-        next_special_id() | (fragment_type as u64)
-    }
-}
-
-pub fn node_id_from_scroll_id(id: usize) -> Option<usize> {
-    if (id as u64 & !SPECIAL_SCROLL_ROOT_ID_MASK) != 0 {
-        return Some(id & !3);
-    }
-    None
-}
-
-pub trait WebrenderApi {
-    fn add_font_instance(
-        &self,
-        font_key: FontKey,
-        size: f32,
-        flags: FontInstanceFlags,
-    ) -> FontInstanceKey;
-    fn add_font(&self, data: Arc<Vec<u8>>, index: u32) -> FontKey;
-    fn add_system_font(&self, handle: NativeFontHandle) -> FontKey;
-}
diff --git a/components/shared/msg/lib.rs b/components/shared/msg/lib.rs
deleted file mode 100644
index b2ce3a52c2c..00000000000
--- a/components/shared/msg/lib.rs
+++ /dev/null
@@ -1,7 +0,0 @@
-/* This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
-
-#![deny(unsafe_code)]
-
-pub mod constellation_msg;
diff --git a/components/shared/net/Cargo.toml b/components/shared/net/Cargo.toml
index 50e9d4eb21d..73db752aba6 100644
--- a/components/shared/net/Cargo.toml
+++ b/components/shared/net/Cargo.toml
@@ -13,6 +13,7 @@ test = false
 doctest = false
 
 [dependencies]
+base = { workspace = true }
 content-security-policy = { workspace = true }
 cookie = { workspace = true }
 embedder_traits = { workspace = true }
@@ -27,7 +28,6 @@ log = { workspace = true }
 malloc_size_of = { workspace = true }
 malloc_size_of_derive = { workspace = true }
 mime = { workspace = true }
-msg = { workspace = true }
 num-traits = { workspace = true }
 percent-encoding = { workspace = true }
 pixels = { path = "../../pixels" }
diff --git a/components/shared/net/lib.rs b/components/shared/net/lib.rs
index 95f8856689d..436ccf5d645 100644
--- a/components/shared/net/lib.rs
+++ b/components/shared/net/lib.rs
@@ -6,6 +6,7 @@
 
 use std::time::{SystemTime, UNIX_EPOCH};
 
+use base::id::HistoryStateId;
 use cookie::Cookie;
 use headers::{ContentType, HeaderMapExt, ReferrerPolicy as ReferrerPolicyHeader};
 use http::{Error as HttpError, HeaderMap, StatusCode};
@@ -19,7 +20,6 @@ use log::warn;
 use malloc_size_of::malloc_size_of_is_0;
 use malloc_size_of_derive::MallocSizeOf;
 use mime::Mime;
-use msg::constellation_msg::HistoryStateId;
 use num_traits::Zero;
 use rustls::Certificate;
 use serde::{Deserialize, Serialize};
diff --git a/components/shared/net/request.rs b/components/shared/net/request.rs
index 346614bc73e..77b37e17b75 100644
--- a/components/shared/net/request.rs
+++ b/components/shared/net/request.rs
@@ -4,13 +4,13 @@
 
 use std::sync::{Arc, Mutex};
 
+use base::id::PipelineId;
 use content_security_policy::{self as csp, CspList};
 use http::header::{HeaderName, AUTHORIZATION};
 use http::{HeaderMap, Method};
 use ipc_channel::ipc::{self, IpcReceiver, IpcSender};
 use malloc_size_of_derive::MallocSizeOf;
 use mime::Mime;
-use msg::constellation_msg::PipelineId;
 use serde::{Deserialize, Serialize};
 use servo_url::{ImmutableOrigin, ServoUrl};
 
diff --git a/components/shared/script/Cargo.toml b/components/shared/script/Cargo.toml
index 5cc2b1f8554..f95a0ffdcc9 100644
--- a/components/shared/script/Cargo.toml
+++ b/components/shared/script/Cargo.toml
@@ -11,6 +11,8 @@ name = "script_traits"
 path = "lib.rs"
 
 [dependencies]
+background_hang_monitor_api = { workspace = true }
+base = { workspace = true }
 bitflags = { workspace = true }
 bluetooth_traits = { workspace = true }
 canvas_traits = { workspace = true }
@@ -29,7 +31,6 @@ log = { workspace = true }
 malloc_size_of = { workspace = true }
 malloc_size_of_derive = { workspace = true }
 media = { path = "../../media" }
-msg = { workspace = true }
 net_traits = { workspace = true }
 pixels = { path = "../../pixels" }
 profile_traits = { workspace = true }
diff --git a/components/shared/script/lib.rs b/components/shared/script/lib.rs
index 35f7520684e..2f9822d2711 100644
--- a/components/shared/script/lib.rs
+++ b/components/shared/script/lib.rs
@@ -20,6 +20,12 @@ use std::collections::{HashMap, VecDeque};
 use std::fmt;
 use std::sync::Arc;
 
+use background_hang_monitor_api::BackgroundHangMonitorRegister;
+use base::id::{
+    BlobId, BrowsingContextId, HistoryStateId, MessagePortId, PipelineId, PipelineNamespaceId,
+    TopLevelBrowsingContextId,
+};
+use base::Epoch;
 use bitflags::bitflags;
 use bluetooth_traits::BluetoothRequest;
 use canvas_traits::webgl::WebGLPipeline;
@@ -29,7 +35,6 @@ use devtools_traits::{DevtoolScriptControlMsg, ScriptToDevtoolsControlMsg, Worke
 use embedder_traits::{CompositorEventVariant, Cursor};
 use euclid::default::Point2D;
 use euclid::{Length, Rect, Scale, Size2D, UnknownUnit, Vector2D};
-use gfx_traits::Epoch;
 use http::{HeaderMap, Method};
 use ipc_channel::ipc::{self, IpcReceiver, IpcSender};
 use ipc_channel::Error as IpcError;
@@ -40,10 +45,6 @@ use log::warn;
 use malloc_size_of::malloc_size_of_is_0;
 use malloc_size_of_derive::MallocSizeOf;
 use media::WindowGLContext;
-use msg::constellation_msg::{
-    BackgroundHangMonitorRegister, BlobId, BrowsingContextId, HistoryStateId, MessagePortId,
-    PipelineId, PipelineNamespaceId, TopLevelBrowsingContextId,
-};
 use net_traits::image::base::Image;
 use net_traits::image_cache::ImageCache;
 use net_traits::request::{Referrer, RequestBody};
@@ -66,7 +67,7 @@ use crate::compositor::CompositorDisplayListInfo;
 pub use crate::script_msg::{
     DOMMessage, EventResult, HistoryEntryReplacement, IFrameSizeMsg, Job, JobError, JobResult,
     JobResultValue, JobType, LayoutMsg, LogEntry, SWManagerMsg, SWManagerSenders, ScopeThings,
-    ScriptMsg, ServiceWorkerMsg,
+    ScriptMsg, ServiceWorkerMsg, TraversalDirection,
 };
 use crate::serializable::{BlobData, BlobImpl};
 use crate::transferable::MessagePortImpl;
diff --git a/components/shared/script/script_msg.rs b/components/shared/script/script_msg.rs
index a51859231ba..d750d33340d 100644
--- a/components/shared/script/script_msg.rs
+++ b/components/shared/script/script_msg.rs
@@ -5,18 +5,18 @@
 use std::collections::{HashMap, VecDeque};
 use std::fmt;
 
+use base::id::{
+    BroadcastChannelRouterId, BrowsingContextId, HistoryStateId, MessagePortId,
+    MessagePortRouterId, PipelineId, ServiceWorkerId, ServiceWorkerRegistrationId,
+    TopLevelBrowsingContextId,
+};
+use base::Epoch;
 use canvas_traits::canvas::{CanvasId, CanvasMsg};
 use devtools_traits::{ScriptToDevtoolsControlMsg, WorkerId};
 use embedder_traits::{EmbedderMsg, MediaSessionEvent};
 use euclid::default::Size2D as UntypedSize2D;
 use euclid::Size2D;
-use gfx_traits::Epoch;
 use ipc_channel::ipc::{IpcReceiver, IpcSender};
-use msg::constellation_msg::{
-    BroadcastChannelRouterId, BrowsingContextId, HistoryStateId, MessagePortId,
-    MessagePortRouterId, PipelineId, ServiceWorkerId, ServiceWorkerRegistrationId,
-    TopLevelBrowsingContextId, TraversalDirection,
-};
 use net_traits::request::RequestBuilder;
 use net_traits::storage_thread::StorageType;
 use net_traits::CoreResourceMsg;
@@ -492,3 +492,12 @@ pub enum SWManagerMsg {
     /// <https://github.com/servo/servo/issues/24660>
     PostMessageToClient,
 }
+
+/// The direction of a history traversal
+#[derive(Clone, Copy, Debug, Deserialize, Eq, Hash, PartialEq, Serialize)]
+pub enum TraversalDirection {
+    /// Travel forward the given number of documents.
+    Forward(usize),
+    /// Travel backward the given number of documents.
+    Back(usize),
+}
diff --git a/components/shared/script/serializable.rs b/components/shared/script/serializable.rs
index d186cad621a..d168736f961 100644
--- a/components/shared/script/serializable.rs
+++ b/components/shared/script/serializable.rs
@@ -11,8 +11,8 @@
 use std::cell::RefCell;
 use std::path::PathBuf;
 
+use base::id::BlobId;
 use malloc_size_of_derive::MallocSizeOf;
-use msg::constellation_msg::BlobId;
 use net_traits::filemanager_thread::RelativePos;
 use serde::{Deserialize, Serialize};
 use uuid::Uuid;
diff --git a/components/shared/script/transferable.rs b/components/shared/script/transferable.rs
index 2daf4a8d3fd..8344dd493b0 100644
--- a/components/shared/script/transferable.rs
+++ b/components/shared/script/transferable.rs
@@ -9,8 +9,8 @@
 
 use std::collections::VecDeque;
 
+use base::id::MessagePortId;
 use malloc_size_of_derive::MallocSizeOf;
-use msg::constellation_msg::MessagePortId;
 use serde::{Deserialize, Serialize};
 
 use crate::PortMessageTask;
diff --git a/components/shared/script/webdriver_msg.rs b/components/shared/script/webdriver_msg.rs
index d72d93b61cb..9108f2dcbd2 100644
--- a/components/shared/script/webdriver_msg.rs
+++ b/components/shared/script/webdriver_msg.rs
@@ -6,11 +6,11 @@
 
 use std::collections::HashMap;
 
+use base::id::BrowsingContextId;
 use cookie::Cookie;
 use euclid::default::Rect;
 use hyper_serde::Serde;
 use ipc_channel::ipc::IpcSender;
-use msg::constellation_msg::BrowsingContextId;
 use serde::{Deserialize, Serialize};
 use servo_url::ServoUrl;
 use webdriver::common::{WebElement, WebFrame, WebWindow};
diff --git a/components/shared/script_layout/Cargo.toml b/components/shared/script_layout/Cargo.toml
index df526c9bec9..57c4059b859 100644
--- a/components/shared/script_layout/Cargo.toml
+++ b/components/shared/script_layout/Cargo.toml
@@ -11,6 +11,7 @@ name = "script_layout_interface"
 path = "lib.rs"
 
 [dependencies]
+base = { workspace = true }
 app_units = { workspace = true }
 atomic_refcell = { workspace = true }
 canvas_traits = { workspace = true }
@@ -24,12 +25,12 @@ libc = { workspace = true }
 malloc_size_of = { workspace = true }
 malloc_size_of_derive = { workspace = true }
 metrics = { path = "../../metrics" }
-msg = { workspace = true }
 net_traits = { workspace = true }
 profile_traits = { workspace = true }
 range = { path = "../../range" }
 script_traits = { workspace = true }
 selectors = { workspace = true }
+serde = { workspace = true }
 servo_arc = { workspace = true }
 servo_atoms = { workspace = true }
 servo_url = { path = "../../url" }
diff --git a/components/shared/script_layout/lib.rs b/components/shared/script_layout/lib.rs
index d4ac0185306..7c1f4ee2162 100644
--- a/components/shared/script_layout/lib.rs
+++ b/components/shared/script_layout/lib.rs
@@ -12,22 +12,22 @@ pub mod wrapper_traits;
 
 use std::any::Any;
 use std::borrow::Cow;
-use std::sync::atomic::AtomicIsize;
+use std::sync::atomic::{AtomicIsize, AtomicU64, Ordering};
 use std::sync::Arc;
 
 use app_units::Au;
 use atomic_refcell::AtomicRefCell;
+use base::id::{BrowsingContextId, PipelineId};
+use base::Epoch;
 use canvas_traits::canvas::{CanvasId, CanvasMsg};
 use crossbeam_channel::Sender;
 use euclid::default::{Point2D, Rect};
 use euclid::Size2D;
 use gfx::font_cache_thread::FontCacheThread;
-use gfx_traits::Epoch;
 use ipc_channel::ipc::IpcSender;
 use libc::c_void;
 use malloc_size_of_derive::MallocSizeOf;
 use metrics::PaintTimeMetrics;
-use msg::constellation_msg::{BrowsingContextId, PipelineId};
 use net_traits::image_cache::{ImageCache, PendingImageId};
 use profile_traits::mem::Report;
 use profile_traits::time;
@@ -35,6 +35,7 @@ use script_traits::{
     ConstellationControlMsg, InitialScriptState, LayoutControlMsg, LayoutMsg, LoadData, Painter,
     ScrollState, UntrustedNodeAddress, WebrenderIpcSender, WindowSizeData,
 };
+use serde::{Deserialize, Serialize};
 use servo_arc::Arc as ServoArc;
 use servo_url::{ImmutableOrigin, ServoUrl};
 use style::animation::DocumentAnimationSet;
@@ -413,3 +414,50 @@ pub struct PendingRestyle {
     /// Any explicit restyles damage that have been accumulated for this element.
     pub damage: RestyleDamage,
 }
+
+/// The type of fragment that a scroll root is created for.
+///
+/// This can only ever grow to maximum 4 entries. That's because we cram the value of this enum
+/// into the lower 2 bits of the `ScrollRootId`, which otherwise contains a 32-bit-aligned
+/// heap address.
+#[derive(Clone, Copy, Debug, Deserialize, Eq, Hash, MallocSizeOf, PartialEq, Serialize)]
+pub enum FragmentType {
+    /// A StackingContext for the fragment body itself.
+    FragmentBody,
+    /// A StackingContext created to contain ::before pseudo-element content.
+    BeforePseudoContent,
+    /// A StackingContext created to contain ::after pseudo-element content.
+    AfterPseudoContent,
+}
+
+/// The next ID that will be used for a special scroll root id.
+///
+/// A special scroll root is a scroll root that is created for generated content.
+static NEXT_SPECIAL_SCROLL_ROOT_ID: AtomicU64 = AtomicU64::new(0);
+
+/// If none of the bits outside this mask are set, the scroll root is a special scroll root.
+/// Note that we assume that the top 16 bits of the address space are unused on the platform.
+const SPECIAL_SCROLL_ROOT_ID_MASK: u64 = 0xffff;
+
+/// Returns a new scroll root ID for a scroll root.
+fn next_special_id() -> u64 {
+    // We shift this left by 2 to make room for the fragment type ID.
+    ((NEXT_SPECIAL_SCROLL_ROOT_ID.fetch_add(1, Ordering::SeqCst) + 1) << 2) &
+        SPECIAL_SCROLL_ROOT_ID_MASK
+}
+
+pub fn combine_id_with_fragment_type(id: usize, fragment_type: FragmentType) -> u64 {
+    debug_assert_eq!(id & (fragment_type as usize), 0);
+    if fragment_type == FragmentType::FragmentBody {
+        id as u64
+    } else {
+        next_special_id() | (fragment_type as u64)
+    }
+}
+
+pub fn node_id_from_scroll_id(id: usize) -> Option<usize> {
+    if (id as u64 & !SPECIAL_SCROLL_ROOT_ID_MASK) != 0 {
+        return Some(id & !3);
+    }
+    None
+}
diff --git a/components/shared/script_layout/wrapper_traits.rs b/components/shared/script_layout/wrapper_traits.rs
index 846943414ae..0adb51be244 100644
--- a/components/shared/script_layout/wrapper_traits.rs
+++ b/components/shared/script_layout/wrapper_traits.rs
@@ -9,9 +9,9 @@ use std::fmt::Debug;
 use std::sync::Arc as StdArc;
 
 use atomic_refcell::AtomicRef;
-use gfx_traits::{ByteIndex, FragmentType};
+use base::id::{BrowsingContextId, PipelineId};
+use gfx_traits::ByteIndex;
 use html5ever::{local_name, namespace_url, ns, LocalName, Namespace};
-use msg::constellation_msg::{BrowsingContextId, PipelineId};
 use net_traits::image::base::{Image, ImageMetadata};
 use range::Range;
 use servo_arc::Arc;
@@ -25,7 +25,8 @@ use style::selector_parser::{PseudoElement, PseudoElementCascadeType, SelectorIm
 use style::stylist::RuleInclusion;
 
 use crate::{
-    GenericLayoutData, HTMLCanvasData, HTMLMediaData, LayoutNodeType, SVGSVGData, StyleData,
+    FragmentType, GenericLayoutData, HTMLCanvasData, HTMLMediaData, LayoutNodeType, SVGSVGData,
+    StyleData,
 };
 
 pub trait LayoutDataTrait: Default + Send + Sync + 'static {}
diff --git a/components/shared/webrender/lib.rs b/components/shared/webrender/lib.rs
index a71f9f67760..8af3a17b609 100644
--- a/components/shared/webrender/lib.rs
+++ b/components/shared/webrender/lib.rs
@@ -9,7 +9,10 @@ use std::sync::{Arc, Mutex};
 
 use euclid::default::Size2D;
 use webrender_api::units::TexelRect;
-use webrender_api::{ExternalImage, ExternalImageHandler, ExternalImageId, ExternalImageSource};
+use webrender_api::{
+    ExternalImage, ExternalImageHandler, ExternalImageId, ExternalImageSource, FontInstanceFlags,
+    FontInstanceKey, FontKey, NativeFontHandle,
+};
 
 /// This trait is used as a bridge between the different GL clients
 /// in Servo that handles WebRender ExternalImages and the WebRender
@@ -164,3 +167,14 @@ impl ExternalImageHandler for WebrenderExternalImageHandlers {
         };
     }
 }
+
+pub trait WebRenderFontApi {
+    fn add_font_instance(
+        &self,
+        font_key: FontKey,
+        size: f32,
+        flags: FontInstanceFlags,
+    ) -> FontInstanceKey;
+    fn add_font(&self, data: Arc<Vec<u8>>, index: u32) -> FontKey;
+    fn add_system_font(&self, handle: NativeFontHandle) -> FontKey;
+}
diff --git a/components/webdriver_server/Cargo.toml b/components/webdriver_server/Cargo.toml
index d67ef421693..d0871e205bf 100644
--- a/components/webdriver_server/Cargo.toml
+++ b/components/webdriver_server/Cargo.toml
@@ -11,6 +11,7 @@ name = "webdriver_server"
 path = "lib.rs"
 
 [dependencies]
+base = { workspace = true }
 base64 = { workspace = true }
 compositing_traits = { workspace = true }
 cookie = { workspace = true }
@@ -21,7 +22,6 @@ image = { workspace = true }
 ipc-channel = { workspace = true }
 keyboard-types = { workspace = true }
 log = { workspace = true }
-msg = { workspace = true }
 net_traits = { workspace = true }
 pixels = { path = "../pixels" }
 script_traits = { workspace = true }
diff --git a/components/webdriver_server/lib.rs b/components/webdriver_server/lib.rs
index 2793be805b1..6bdfb645c4e 100644
--- a/components/webdriver_server/lib.rs
+++ b/components/webdriver_server/lib.rs
@@ -16,6 +16,7 @@ use std::net::{SocketAddr, SocketAddrV4};
 use std::time::Duration;
 use std::{fmt, mem, thread};
 
+use base::id::{BrowsingContextId, TopLevelBrowsingContextId};
 use base64::Engine;
 use capabilities::ServoCapabilities;
 use compositing_traits::ConstellationMsg;
@@ -27,14 +28,13 @@ use ipc_channel::ipc::{self, IpcSender};
 use ipc_channel::router::ROUTER;
 use keyboard_types::webdriver::send_keys;
 use log::{debug, info};
-use msg::constellation_msg::{BrowsingContextId, TopLevelBrowsingContextId, TraversalDirection};
 use net_traits::request::Referrer;
 use pixels::PixelFormat;
 use script_traits::webdriver_msg::{
     LoadStatus, WebDriverCookieError, WebDriverFrameId, WebDriverJSError, WebDriverJSResult,
     WebDriverJSValue, WebDriverScriptCommand,
 };
-use script_traits::{LoadData, LoadOrigin, WebDriverCommandMsg};
+use script_traits::{LoadData, LoadOrigin, TraversalDirection, WebDriverCommandMsg};
 use serde::de::{Deserializer, MapAccess, Visitor};
 use serde::ser::Serializer;
 use serde::{Deserialize, Serialize};
diff --git a/components/webgpu/Cargo.toml b/components/webgpu/Cargo.toml
index f9e0f9d7c7a..2926cef6fce 100644
--- a/components/webgpu/Cargo.toml
+++ b/components/webgpu/Cargo.toml
@@ -12,11 +12,11 @@ path = "lib.rs"
 
 [dependencies]
 arrayvec = { workspace = true, features = ["serde"] }
+base = { workspace = true }
 euclid = { workspace = true }
 ipc-channel = { workspace = true }
 log = { workspace = true }
 malloc_size_of = { workspace = true }
-msg = { workspace = true }
 serde = { workspace = true, features = ["serde_derive"] }
 servo_config = { path = "../config" }
 smallvec = { workspace = true, features = ["serde"] }
diff --git a/components/webgpu/dom_messages.rs b/components/webgpu/dom_messages.rs
index 6edd6f93e88..1bf37233ad6 100644
--- a/components/webgpu/dom_messages.rs
+++ b/components/webgpu/dom_messages.rs
@@ -7,8 +7,8 @@
 use std::borrow::Cow;
 
 use arrayvec::ArrayVec;
+use base::id::PipelineId;
 use ipc_channel::ipc::{IpcSender, IpcSharedMemory};
-use msg::constellation_msg::PipelineId;
 use serde::{Deserialize, Serialize};
 use smallvec::SmallVec;
 use webrender_api::{ExternalImageId, ImageData, ImageDescriptor, ImageKey};
diff --git a/components/webgpu/script_messages.rs b/components/webgpu/script_messages.rs
index 08e2269d39c..74a827d6dd1 100644
--- a/components/webgpu/script_messages.rs
+++ b/components/webgpu/script_messages.rs
@@ -4,7 +4,7 @@
 
 //! IPC massages that are send to script thread (global scope).
 
-use msg::constellation_msg::PipelineId;
+use base::id::PipelineId;
 use serde::{Deserialize, Serialize};
 
 use crate::identity::WebGPUDevice;
diff --git a/components/webgpu/wgpu_thread.rs b/components/webgpu/wgpu_thread.rs
index 372e8734f2b..9faec2eb5a4 100644
--- a/components/webgpu/wgpu_thread.rs
+++ b/components/webgpu/wgpu_thread.rs
@@ -10,10 +10,10 @@ use std::slice;
 use std::sync::{Arc, Mutex};
 
 use arrayvec::ArrayVec;
+use base::id::PipelineId;
 use euclid::default::Size2D;
 use ipc_channel::ipc::{IpcReceiver, IpcSender, IpcSharedMemory};
 use log::{error, warn};
-use msg::constellation_msg::PipelineId;
 use webrender::{RenderApi, RenderApiSender, Transaction};
 use webrender_api::{DirtyRect, DocumentId};
 use webrender_traits::{WebrenderExternalImageRegistry, WebrenderImageHandlerType};
diff --git a/ports/jniapi/src/simpleservo.rs b/ports/jniapi/src/simpleservo.rs
index d13fb2668ab..cf9a65bbe02 100644
--- a/ports/jniapi/src/simpleservo.rs
+++ b/ports/jniapi/src/simpleservo.rs
@@ -12,6 +12,7 @@ use std::rc::Rc;
 use getopts::Options;
 use ipc_channel::ipc::IpcSender;
 use log::{debug, info, warn};
+use servo::base::id::WebViewId;
 use servo::compositing::windowing::{
     AnimationState, EmbedderCoordinates, EmbedderEvent, EmbedderMethods, MouseWindowEvent,
     WindowMethods,
@@ -21,18 +22,17 @@ use servo::config::prefs::pref_map;
 pub use servo::config::prefs::{add_user_prefs, PrefValue};
 use servo::embedder_traits::resources::{self, Resource, ResourceReaderMethods};
 pub use servo::embedder_traits::{
-    ContextMenuResult, MediaSessionPlaybackState, PermissionPrompt, PermissionRequest, PromptResult,
+    ContextMenuResult, InputMethodType, MediaSessionPlaybackState, PermissionPrompt,
+    PermissionRequest, PromptResult,
 };
 use servo::embedder_traits::{
     EmbedderMsg, EmbedderProxy, MediaSessionEvent, PromptDefinition, PromptOrigin,
 };
 use servo::euclid::{Point2D, Rect, Scale, Size2D, Vector2D};
 use servo::keyboard_types::{Key, KeyState, KeyboardEvent};
-pub use servo::msg::constellation_msg::InputMethodType;
-use servo::msg::constellation_msg::{TraversalDirection, WebViewId};
 use servo::rendering_context::RenderingContext;
 pub use servo::script_traits::{MediaSessionActionType, MouseButton};
-use servo::script_traits::{TouchEventType, TouchId};
+use servo::script_traits::{TouchEventType, TouchId, TraversalDirection};
 use servo::servo_config::{opts, pref};
 use servo::servo_url::ServoUrl;
 pub use servo::webrender_api::units::DeviceIntRect;
diff --git a/ports/servoshell/minibrowser.rs b/ports/servoshell/minibrowser.rs
index c76efee85c0..af2ce8e2d68 100644
--- a/ports/servoshell/minibrowser.rs
+++ b/ports/servoshell/minibrowser.rs
@@ -18,8 +18,8 @@ use gleam::gl;
 use glow::NativeFramebuffer;
 use log::{trace, warn};
 use servo::compositing::windowing::EmbedderEvent;
-use servo::msg::constellation_msg::TraversalDirection;
 use servo::rendering_context::RenderingContext;
+use servo::script_traits::TraversalDirection;
 use servo::servo_geometry::DeviceIndependentPixel;
 use servo::servo_url::ServoUrl;
 use servo::style_traits::DevicePixel;
diff --git a/ports/servoshell/webview.rs b/ports/servoshell/webview.rs
index bbacdb1337d..87795f7a550 100644
--- a/ports/servoshell/webview.rs
+++ b/ports/servoshell/webview.rs
@@ -15,14 +15,15 @@ use euclid::{Point2D, Vector2D};
 use gilrs::{EventType, Gilrs};
 use keyboard_types::{Key, KeyboardEvent, Modifiers, ShortcutMatcher};
 use log::{debug, error, info, trace, warn};
+use servo::base::id::TopLevelBrowsingContextId as WebViewId;
 use servo::compositing::windowing::{EmbedderEvent, WebRenderDebugOption};
 use servo::embedder_traits::{
     CompositorEventVariant, ContextMenuResult, EmbedderMsg, FilterPattern, PermissionPrompt,
     PermissionRequest, PromptDefinition, PromptOrigin, PromptResult,
 };
-use servo::msg::constellation_msg::{TopLevelBrowsingContextId as WebViewId, TraversalDirection};
 use servo::script_traits::{
     GamepadEvent, GamepadIndex, GamepadInputBounds, GamepadUpdateType, TouchEventType,
+    TraversalDirection,
 };
 use servo::servo_config::opts;
 use servo::servo_url::ServoUrl;
diff --git a/python/servo/testing_commands.py b/python/servo/testing_commands.py
index 22a3110902a..cf131f8b319 100644
--- a/python/servo/testing_commands.py
+++ b/python/servo/testing_commands.py
@@ -153,7 +153,6 @@ class MachCommands(CommandBase):
             "hyper_serde",
             "layout_2013",
             "layout_2020",
-            "msg",
             "net",
             "net_traits",
             "selectors",
diff --git a/tests/unit/metrics/Cargo.toml b/tests/unit/metrics/Cargo.toml
index 580d14cef5c..7f410d5701a 100644
--- a/tests/unit/metrics/Cargo.toml
+++ b/tests/unit/metrics/Cargo.toml
@@ -11,10 +11,10 @@ path = "lib.rs"
 doctest = false
 
 [dependencies]
+base = { workspace = true }
 gfx_traits = { workspace = true }
 ipc-channel = { workspace = true }
 metrics = { path = "../../../components/metrics" }
-msg = { workspace = true }
 profile_traits = { workspace = true }
 servo_url = { path = "../../../components/url" }
 time = { workspace = true }
diff --git a/tests/unit/metrics/paint_time.rs b/tests/unit/metrics/paint_time.rs
index 65316e09d16..fc708d3d5ab 100644
--- a/tests/unit/metrics/paint_time.rs
+++ b/tests/unit/metrics/paint_time.rs
@@ -2,10 +2,10 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
-use gfx_traits::Epoch;
+use base::id::TEST_PIPELINE_ID;
+use base::Epoch;
 use ipc_channel::ipc;
 use metrics::{PaintTimeMetrics, ProfilerMetadataFactory, ProgressiveWebMetric};
-use msg::constellation_msg::TEST_PIPELINE_ID;
 use profile_traits::time::{ProfilerChan, TimerMetadata};
 use servo_url::ServoUrl;