Initial internal support for multiple webviews (#31417)

* Add multiple concurrent top-level browsing contexts

Co-authored-by: Delan Azabani <dazabani@igalia.com>

* Rename variables and comments

There are some variable and comments still use browser as names.
This commit renames them to webview.

* Update log message from web view to webview

* Revert offscreen_framebuffer_id rename

* Rename all web view to webview

* Cargo fmt

* Fix viewport/event/clear coordinates when multiview is disabled

* Only deprecate things when multiview is enabled

* Update WebViewManger with shown and invisible sets

Replace visible_webviews and native_window_is_visible with shown_webviews
and invisible_webviews. Add 4 more methods to set them accordingly. The
behavior of is_effectively_visible will return true if the wbview is in
shown_webviews set but not in invisible_webviews.

* Update variant behaviors

* Rename WebViewVisibilityChanged to MarkWebViewInvisible

* Fix unit test by marking id 3 visible again

* Update MarkWebViewInvisible and add UnmarkWebViewInvisible

* Update format and doc comments

* Clean up doc comments

* Address style and naming changes

* Rename UpdateWebView to UpdateFrameTreeForWebView

* constellation: send frame tree unconditionally over focus and feature

* Clarify shown and invisible sets in constellation WebViewManager

* Eliminate forward_to_constellation!()

* Actually remove the unused macro

* Don’t gate compositor changes on multiview feature flag

* Update todo in mouse event dispatch

* Pass all visible webview ids in a single ReadyToPresent message

* Fix compile and lint errors

* servoshell: fix gap between minibrowser toolbar and webview

* Fix failure in /_mozilla/mozilla/window_resizeTo.html

* Fix compile warnings

* Remove stray dbg!()

* Remove confusing “effectively visible” logic (see #31815, #31816)

* Allow embedder to show/hide/raise webviews without ipc

* Update root pipeline only when painting order actually changes

* Stop gating old focus and SetFrameTree behaviour behind Cargo feature

* Use webview_id and WebViewId in webview-related code

* Improve logging of webview-related embedder events

* Allow webview Show and Raise events to optionally hide all others

* Don’t do anything in response to WebViewPaintingOrder

* Remove WebViewPaintingOrder, since its payload is unreliable

* On MoveResizeWebView, only update root pipeline if rect changed

* Rename IOCompositor methods for clarity

* compositor: add event tracing; log webview ops even without ipc

* Add temporary debug logging

* Add more temporary debug logging

* Remove temporary logging in compositor

* Remove temporary debug logging

* Add temporary debug logging, but defer I/O until panic

* Capture a backtrace with each crash log entry

* Proper error handling without panicking in WebViewManager

* Clean up imports in constellation

---------

Co-authored-by: Delan Azabani <dazabani@igalia.com>
Co-authored-by: Martin Robinson <mrobinson@igalia.com>

3 files changed, 55 insertions, 21 deletions

diff --git a/components/shared/compositing/constellation_msg.rs b/components/shared/compositing/constellation_msg.rs
index 8204ec6d2e3..64d593ee08c 100644
--- a/components/shared/compositing/constellation_msg.rs
+++ b/components/shared/compositing/constellation_msg.rs
@@ -11,13 +11,14 @@ use gfx_traits::Epoch;
 use ipc_channel::ipc::IpcSender;
 use keyboard_types::KeyboardEvent;
 use msg::constellation_msg::{
-    BrowsingContextId, PipelineId, TopLevelBrowsingContextId, TraversalDirection,
+    BrowsingContextId, PipelineId, TopLevelBrowsingContextId, TraversalDirection, WebViewId,
 };
 use script_traits::{
     AnimationTickType, CompositorEvent, GamepadEvent, LogEntry, MediaSessionActionType,
     WebDriverCommandMsg, WindowSizeData, WindowSizeType,
 };
 use servo_url::ServoUrl;
+use webrender_api::units::DeviceRect;
 
 /// Messages to the constellation.
 pub enum ConstellationMsg {
@@ -60,9 +61,17 @@ pub enum ConstellationMsg {
     CloseWebView(TopLevelBrowsingContextId),
     /// Panic a top level browsing context.
     SendError(Option<TopLevelBrowsingContextId>, String),
-    /// Make a top-level browsing context focused.
+    /// Move and/or resize a webview to the given rect.
+    MoveResizeWebView(TopLevelBrowsingContextId, DeviceRect),
+    /// Start painting a webview, and optionally stop painting all others.
+    ShowWebView(TopLevelBrowsingContextId, bool),
+    /// Stop painting a webview.
+    HideWebView(TopLevelBrowsingContextId),
+    /// Start painting a webview on top of all others, and optionally stop painting all others.
+    RaiseWebViewToTop(TopLevelBrowsingContextId, bool),
+    /// Make a webview focused.
     FocusWebView(TopLevelBrowsingContextId),
-    /// Make none of the top-level browsing contexts focused.
+    /// Make none of the webviews focused.
     BlurWebView,
     /// Forward an event to the script task of the given pipeline.
     ForwardEvent(PipelineId, CompositorEvent),
@@ -80,16 +89,23 @@ pub enum ConstellationMsg {
     SetWebViewThrottled(TopLevelBrowsingContextId, bool),
     /// Virtual keyboard was dismissed
     IMEDismissed,
-    /// Compositing done, but external code needs to present.
-    ReadyToPresent(TopLevelBrowsingContextId),
+    /// Notify the embedder that it needs to present a new frame.
+    ReadyToPresent(Vec<WebViewId>),
     /// Gamepad state has changed
     Gamepad(GamepadEvent),
 }
 
 impl fmt::Debug for ConstellationMsg {
     fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        write!(formatter, "ConstellationMsg::{}", self.variant_name())
+    }
+}
+
+impl ConstellationMsg {
+    /// Return the variant name, for error logging that happens after the message is consumed.
+    pub fn variant_name(&self) -> &'static str {
         use self::ConstellationMsg::*;
-        let variant = match *self {
+        match *self {
             Exit => "Exit",
             GetBrowsingContext(..) => "GetBrowsingContext",
             GetPipeline(..) => "GetPipeline",
@@ -106,6 +122,10 @@ impl fmt::Debug for ConstellationMsg {
             LogEntry(..) => "LogEntry",
             NewWebView(..) => "NewWebView",
             CloseWebView(..) => "CloseWebView",
+            MoveResizeWebView(..) => "MoveResizeWebView",
+            ShowWebView(..) => "ShowWebView",
+            HideWebView(..) => "HideWebView",
+            RaiseWebViewToTop(..) => "RaiseWebViewToTop",
             FocusWebView(..) => "FocusWebView",
             BlurWebView => "BlurWebView",
             SendError(..) => "SendError",
@@ -120,7 +140,6 @@ impl fmt::Debug for ConstellationMsg {
             ClearCache => "ClearCache",
             ReadyToPresent(..) => "ReadyToPresent",
             Gamepad(..) => "Gamepad",
-        };
-        write!(formatter, "ConstellationMsg::{}", variant)
+        }
     }
 }
diff --git a/components/shared/compositing/lib.rs b/components/shared/compositing/lib.rs
index 8ab45b374ed..9c759bc4acf 100644
--- a/components/shared/compositing/lib.rs
+++ b/components/shared/compositing/lib.rs
@@ -24,7 +24,7 @@ use script_traits::{
     ScriptToCompositorMsg,
 };
 use style_traits::CSSPixel;
-use webrender_api::units::{DeviceIntPoint, DeviceIntSize};
+use webrender_api::units::{DeviceIntPoint, DeviceIntSize, DeviceRect};
 use webrender_api::{self, FontInstanceKey, FontKey, ImageKey};
 
 /// Sends messages to the compositor.
@@ -73,8 +73,18 @@ pub enum CompositorMsg {
     ShutdownComplete,
     /// Alerts the compositor that the given pipeline has changed whether it is running animations.
     ChangeRunningAnimationsState(PipelineId, AnimationState),
-    /// Replaces the current frame tree, typically called during main frame navigation.
-    SetFrameTree(SendableFrameTree),
+    /// Create or update a webview, given its frame tree.
+    CreateOrUpdateWebView(SendableFrameTree),
+    /// Remove a webview.
+    RemoveWebView(TopLevelBrowsingContextId),
+    /// Move and/or resize a webview to the given rect.
+    MoveResizeWebView(TopLevelBrowsingContextId, DeviceRect),
+    /// Start painting a webview, and optionally stop painting all others.
+    ShowWebView(TopLevelBrowsingContextId, bool),
+    /// Stop painting a webview.
+    HideWebView(TopLevelBrowsingContextId),
+    /// Start painting a webview on top of all others, and optionally stop painting all others.
+    RaiseWebViewToTop(TopLevelBrowsingContextId, bool),
     /// Script has handled a touch event, and either prevented or allowed default actions.
     TouchEventProcessed(EventResult),
     /// Composite to a PNG file and return the Image over a passed channel.
@@ -153,7 +163,12 @@ impl Debug for CompositorMsg {
             CompositorMsg::ChangeRunningAnimationsState(_, state) => {
                 write!(f, "ChangeRunningAnimationsState({:?})", state)
             },
-            CompositorMsg::SetFrameTree(..) => write!(f, "SetFrameTree"),
+            CompositorMsg::CreateOrUpdateWebView(..) => write!(f, "CreateOrUpdateWebView"),
+            CompositorMsg::RemoveWebView(..) => write!(f, "RemoveWebView"),
+            CompositorMsg::MoveResizeWebView(..) => write!(f, "MoveResizeWebView"),
+            CompositorMsg::ShowWebView(..) => write!(f, "ShowWebView"),
+            CompositorMsg::HideWebView(..) => write!(f, "HideWebView"),
+            CompositorMsg::RaiseWebViewToTop(..) => write!(f, "RaiseWebViewToTop"),
             CompositorMsg::TouchEventProcessed(..) => write!(f, "TouchEventProcessed"),
             CompositorMsg::CreatePng(..) => write!(f, "CreatePng"),
             CompositorMsg::IsReadyToSaveImageReply(..) => write!(f, "IsReadyToSaveImageReply"),
diff --git a/components/shared/embedder/lib.rs b/components/shared/embedder/lib.rs
index da6eca45291..0acf7d01ce5 100644
--- a/components/shared/embedder/lib.rs
+++ b/components/shared/embedder/lib.rs
@@ -10,7 +10,7 @@ use crossbeam_channel::{Receiver, Sender};
 use ipc_channel::ipc::IpcSender;
 use keyboard_types::KeyboardEvent;
 use log::warn;
-use msg::constellation_msg::{InputMethodType, PipelineId, TopLevelBrowsingContextId};
+use msg::constellation_msg::{InputMethodType, PipelineId, TopLevelBrowsingContextId, WebViewId};
 use num_derive::FromPrimitive;
 use serde::{Deserialize, Serialize};
 use servo_url::ServoUrl;
@@ -156,13 +156,13 @@ pub enum EmbedderMsg {
     AllowNavigationRequest(PipelineId, ServoUrl),
     /// Whether or not to allow script to open a new tab/browser
     AllowOpeningWebView(IpcSender<bool>),
-    /// A browser was created
+    /// A webview was created.
     WebViewOpened(TopLevelBrowsingContextId),
-    /// A browser was destroyed
+    /// A webview was destroyed.
     WebViewClosed(TopLevelBrowsingContextId),
-    /// A browser gained focus for keyboard events
+    /// A webview gained focus for keyboard events.
     WebViewFocused(TopLevelBrowsingContextId),
-    /// All browsers lost focus for keyboard events
+    /// All webviews lost focus for keyboard events.
     WebViewBlurred,
     /// Wether or not to unload a document
     AllowUnload(IpcSender<bool>),
@@ -210,8 +210,8 @@ pub enum EmbedderMsg {
     MediaSessionEvent(MediaSessionEvent),
     /// Report the status of Devtools Server with a token that can be used to bypass the permission prompt.
     OnDevtoolsStarted(Result<u16, ()>, String),
-    /// Compositing done, but external code needs to present.
-    ReadyToPresent,
+    /// Notify the embedder that it needs to present a new frame.
+    ReadyToPresent(Vec<WebViewId>),
     /// The given event was delivered to a pipeline in the given browser.
     EventDelivered(CompositorEventVariant),
 }
@@ -261,12 +261,12 @@ impl Debug for EmbedderMsg {
             EmbedderMsg::WebViewOpened(..) => write!(f, "WebViewOpened"),
             EmbedderMsg::WebViewClosed(..) => write!(f, "WebViewClosed"),
             EmbedderMsg::WebViewFocused(..) => write!(f, "WebViewFocused"),
-            EmbedderMsg::WebViewBlurred => write!(f, "WebViewUnfocused"),
+            EmbedderMsg::WebViewBlurred => write!(f, "WebViewBlurred"),
             EmbedderMsg::ReportProfile(..) => write!(f, "ReportProfile"),
             EmbedderMsg::MediaSessionEvent(..) => write!(f, "MediaSessionEvent"),
             EmbedderMsg::OnDevtoolsStarted(..) => write!(f, "OnDevtoolsStarted"),
             EmbedderMsg::ShowContextMenu(..) => write!(f, "ShowContextMenu"),
-            EmbedderMsg::ReadyToPresent => write!(f, "ReadyToPresent"),
+            EmbedderMsg::ReadyToPresent(..) => write!(f, "ReadyToPresent"),
             EmbedderMsg::EventDelivered(..) => write!(f, "HitTestedEvent"),
         }
     }