Move `*_traits` and other shared types to `shared`

This is the start of the organization of types that are in their own
crates in order to break dependency cycles between other crates. The
idea here is that putting these packages into their own directory is the
first step toward cleaning them up. They have grown organically and it
is difficult to explain to new folks where to put new shared types. Many
of these crates contain more than traits or don't contain traits at all.

Notably, `script_traits` isn't touched because it is vendored from
Gecko. Eventually this will move to `third_party`.

2 files changed, 76 insertions, 0 deletions

diff --git a/components/shared/layout/Cargo.toml b/components/shared/layout/Cargo.toml
new file mode 100644
index 00000000000..c81ed04454c
--- /dev/null
+++ b/components/shared/layout/Cargo.toml
@@ -0,0 +1,23 @@
+[package]
+name = "layout_traits"
+version = "0.0.1"
+authors = ["The Servo Project Developers"]
+license = "MPL-2.0"
+edition = "2018"
+publish = false
+
+[lib]
+name = "layout_traits"
+path = "lib.rs"
+
+[dependencies]
+crossbeam-channel = { workspace = true }
+gfx = { path = "../../gfx" }
+ipc-channel = { workspace = true }
+metrics = { path = "../../metrics" }
+msg = { workspace = true }
+net_traits = { workspace = true }
+profile_traits = { workspace = true }
+script_traits = { workspace = true }
+servo_url = { path = "../../url" }
+webrender_api = { workspace = true }
diff --git a/components/shared/layout/lib.rs b/components/shared/layout/lib.rs
new file mode 100644
index 00000000000..1e1783e489f
--- /dev/null
+++ b/components/shared/layout/lib.rs
@@ -0,0 +1,53 @@
+/* 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)]
+
+// This module contains traits in layout used generically
+//   in the rest of Servo.
+// The traits are here instead of in layout so
+//   that these modules won't have to depend on layout.
+
+use std::sync::atomic::AtomicBool;
+use std::sync::Arc;
+
+use crossbeam_channel::{Receiver, Sender};
+use gfx::font_cache_thread::FontCacheThread;
+use ipc_channel::ipc::{IpcReceiver, IpcSender};
+use metrics::PaintTimeMetrics;
+use msg::constellation_msg::{
+    BackgroundHangMonitorRegister, PipelineId, TopLevelBrowsingContextId,
+};
+use net_traits::image_cache::ImageCache;
+use profile_traits::{mem, time};
+use script_traits::{
+    ConstellationControlMsg, LayoutControlMsg, LayoutMsg as ConstellationMsg, WebrenderIpcSender,
+    WindowSizeData,
+};
+use servo_url::ServoUrl;
+
+// A static method creating a layout thread
+// Here to remove the compositor -> layout dependency
+pub trait LayoutThreadFactory {
+    type Message;
+    fn create(
+        id: PipelineId,
+        top_level_browsing_context_id: TopLevelBrowsingContextId,
+        url: ServoUrl,
+        is_iframe: bool,
+        chan: (Sender<Self::Message>, Receiver<Self::Message>),
+        pipeline_port: IpcReceiver<LayoutControlMsg>,
+        background_hang_monitor: Box<dyn BackgroundHangMonitorRegister>,
+        constellation_chan: IpcSender<ConstellationMsg>,
+        script_chan: IpcSender<ConstellationControlMsg>,
+        image_cache: Arc<dyn ImageCache>,
+        font_cache_thread: FontCacheThread,
+        time_profiler_chan: time::ProfilerChan,
+        mem_profiler_chan: mem::ProfilerChan,
+        webrender_api_sender: WebrenderIpcSender,
+        paint_time_metrics: PaintTimeMetrics,
+        busy: Arc<AtomicBool>,
+        window_size: WindowSizeData,
+    );
+}