servo: Merge #19547 - Send IPC receiver for canvas as part of CreateCanvasPaintThread message (from tigercosmos:b1); r=jdm

<!-- Please describe your changes on the following line: -->
I am not sure if @jdm want this.
r? @jdm

---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: -->
- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix #19483(github issue number if applicable).

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- [ ] There are tests for these changes OR
- [ ] These changes do not require tests because _____

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Source-Repo: https://github.com/servo/servo
Source-Revision: c9e3fabdfd0d4c900e83a1050ec465303e339681

--HG--
extra : subtree_source : https%3A//hg.mozilla.org/projects/converted-servo-linear
extra : subtree_revision : 6aa288e249807e1eae78d5900427d8f72414a4ee

servo/components/canvas/canvas_paint_thread.rs

@@ -11,7 +11,7 @@ use azure::azure_hl::SurfacePattern;
 use canvas_traits::canvas::*;
 use cssparser::RGBA;
 use euclid::{Transform2D, Point2D, Vector2D, Rect, Size2D};
-use ipc_channel::ipc::{self, IpcSender};
+use ipc_channel::ipc::{self, IpcSender, IpcReceiver};
 use num_traits::ToPrimitive;
 use std::borrow::ToOwned;
 use std::mem;
@@ -118,9 +118,8 @@ impl<'a> CanvasPaintThread<'a> {
     /// communicate with it.
     pub fn start(size: Size2D<i32>,
                  webrender_api_sender: webrender_api::RenderApiSender,
-                 antialias: bool)
-                 -> IpcSender<CanvasMsg> {
-        let (sender, receiver) = ipc::channel::<CanvasMsg>().unwrap();
+                 antialias: bool,
+                 receiver: IpcReceiver<CanvasMsg>) {
         let antialias = if antialias {
             AntialiasMode::Default
         } else {
@@ -216,8 +215,6 @@ impl<'a> CanvasPaintThread<'a> {
                 }
             }
         }).expect("Thread spawning failed");
-
-        sender
     }
 
     fn save_context_state(&mut self) {

servo/components/constellation/constellation.rs

@@ -1235,9 +1235,9 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
                     self.embedder_proxy.send(EmbedderMsg::HeadParsed(source_top_ctx_id));
                 }
             }
-            FromScriptMsg::CreateCanvasPaintThread(size, sender) => {
+            FromScriptMsg::CreateCanvasPaintThread(size, receiver) => {
                 debug!("constellation got create-canvas-paint-thread message");
-                self.handle_create_canvas_paint_thread_msg(&size, sender)
+                self.handle_create_canvas_paint_thread_msg(&size, receiver)
             }
             FromScriptMsg::NodeStatus(message) => {
                 debug!("constellation got NodeStatus message");
@@ -2264,13 +2264,12 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
     fn handle_create_canvas_paint_thread_msg(
             &mut self,
             size: &Size2D<i32>,
-            response_sender: IpcSender<IpcSender<CanvasMsg>>) {
+            receiver: IpcReceiver<CanvasMsg>) {
         let webrender_api = self.webrender_api_sender.clone();
-        let sender = CanvasPaintThread::start(*size, webrender_api,
-                                              opts::get().enable_canvas_antialiasing);
-        if let Err(e) = response_sender.send(sender) {
-            warn!("Create canvas paint thread response failed ({})", e);
-        }
+        CanvasPaintThread::start(*size,
+                                 webrender_api,
+                                 opts::get().enable_canvas_antialiasing,
+                                 receiver);
     }
 
     fn handle_webdriver_msg(&mut self, msg: WebDriverCommandMsg) {

servo/components/script/dom/canvasrenderingcontext2d.rs

@@ -129,11 +129,10 @@ impl CanvasRenderingContext2D {
                          size: Size2D<i32>)
                          -> CanvasRenderingContext2D {
         debug!("Creating new canvas rendering context.");
-        let (sender, receiver) = ipc::channel().unwrap();
+        let (ipc_renderer, receiver) = ipc::channel::<CanvasMsg>().unwrap();
         let script_to_constellation_chan = global.script_to_constellation_chan();
         debug!("Asking constellation to create new canvas thread.");
-        script_to_constellation_chan.send(ScriptMsg::CreateCanvasPaintThread(size, sender)).unwrap();
-        let ipc_renderer = receiver.recv().unwrap();
+        script_to_constellation_chan.send(ScriptMsg::CreateCanvasPaintThread(size, receiver)).unwrap();
         debug!("Done.");
         CanvasRenderingContext2D {
             reflector_: Reflector::new(),

servo/components/script_traits/script_msg.rs

@@ -79,7 +79,7 @@ pub enum ScriptMsg {
     ChangeRunningAnimationsState(AnimationState),
     /// Requests that a new 2D canvas thread be created. (This is done in the constellation because
     /// 2D canvases may use the GPU and we don't want to give untrusted content access to the GPU.)
-    CreateCanvasPaintThread(Size2D<i32>, IpcSender<IpcSender<CanvasMsg>>),
+    CreateCanvasPaintThread(Size2D<i32>, IpcReceiver<CanvasMsg>),
     /// Notifies the constellation that this frame has received focus.
     Focus,
     /// Forward an event that was sent to the parent window.