From 0e211d0d8f297084304860e3181eb21880921333 Mon Sep 17 00:00:00 2001
From: Josh Matthews <josh@joshmatthews.net>
Date: Mon, 18 Dec 2017 10:51:00 -0500
Subject: [PATCH] Revert "Send IPC receiver for canvas as part of
 CreateCanvasPaintThread message"

This reverts commit a504c9358b70fcf02bd8f2067fcbd17d16c89439.
---
 components/canvas/canvas_paint_thread.rs          |  9 ++++++---
 components/constellation/constellation.rs         | 15 ++++++++-------
 components/script/dom/canvasrenderingcontext2d.rs |  5 +++--
 components/script_traits/script_msg.rs            |  2 +-
 4 files changed, 18 insertions(+), 13 deletions(-)

diff --git a/components/canvas/canvas_paint_thread.rs b/components/canvas/canvas_paint_thread.rs
index a985ac7a999..bb644c60bef 100644
--- a/components/canvas/canvas_paint_thread.rs
+++ b/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::{IpcSender, IpcReceiver};
+use ipc_channel::ipc::{self, IpcSender, IpcReceiver};
 use num_traits::ToPrimitive;
 use std::borrow::ToOwned;
 use std::mem;
@@ -118,8 +118,9 @@ impl<'a> CanvasPaintThread<'a> {
     /// communicate with it.
     pub fn start(size: Size2D<i32>,
                  webrender_api_sender: webrender_api::RenderApiSender,
-                 antialias: bool,
-                 receiver: IpcReceiver<CanvasMsg>) {
+                 antialias: bool)
+                 -> IpcSender<CanvasMsg> {
+        let (sender, receiver) = ipc::channel::<CanvasMsg>().unwrap();
         let antialias = if antialias {
             AntialiasMode::Default
         } else {
@@ -215,6 +216,8 @@ impl<'a> CanvasPaintThread<'a> {
                 }
             }
         }).expect("Thread spawning failed");
+
+        sender
     }
 
     fn save_context_state(&mut self) {
diff --git a/components/constellation/constellation.rs b/components/constellation/constellation.rs
index 7539a4f149e..ec023e3971b 100644
--- a/components/constellation/constellation.rs
+++ b/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, receiver) => {
+            FromScriptMsg::CreateCanvasPaintThread(size, sender) => {
                 debug!("constellation got create-canvas-paint-thread message");
-                self.handle_create_canvas_paint_thread_msg(&size, receiver)
+                self.handle_create_canvas_paint_thread_msg(&size, sender)
             }
             FromScriptMsg::NodeStatus(message) => {
                 debug!("constellation got NodeStatus message");
@@ -2264,12 +2264,13 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
     fn handle_create_canvas_paint_thread_msg(
             &mut self,
             size: &Size2D<i32>,
-            receiver: IpcReceiver<CanvasMsg>) {
+            response_sender: IpcSender<IpcSender<CanvasMsg>>) {
         let webrender_api = self.webrender_api_sender.clone();
-        CanvasPaintThread::start(*size,
-                                 webrender_api,
-                                 opts::get().enable_canvas_antialiasing,
-                                 receiver);
+        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);
+        }
     }
 
     fn handle_webdriver_msg(&mut self, msg: WebDriverCommandMsg) {
diff --git a/components/script/dom/canvasrenderingcontext2d.rs b/components/script/dom/canvasrenderingcontext2d.rs
index 1c9dc16c445..93d4981d2bb 100644
--- a/components/script/dom/canvasrenderingcontext2d.rs
+++ b/components/script/dom/canvasrenderingcontext2d.rs
@@ -129,10 +129,11 @@ impl CanvasRenderingContext2D {
                          size: Size2D<i32>)
                          -> CanvasRenderingContext2D {
         debug!("Creating new canvas rendering context.");
-        let (ipc_renderer, receiver) = ipc::channel::<CanvasMsg>().unwrap();
+        let (sender, receiver) = ipc::channel().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, receiver)).unwrap();
+        script_to_constellation_chan.send(ScriptMsg::CreateCanvasPaintThread(size, sender)).unwrap();
+        let ipc_renderer = receiver.recv().unwrap();
         debug!("Done.");
         CanvasRenderingContext2D {
             reflector_: Reflector::new(),
diff --git a/components/script_traits/script_msg.rs b/components/script_traits/script_msg.rs
index fdef5cf7a17..a9b5f86d8fe 100644
--- a/components/script_traits/script_msg.rs
+++ b/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>, IpcReceiver<CanvasMsg>),
+    CreateCanvasPaintThread(Size2D<i32>, IpcSender<IpcSender<CanvasMsg>>),
     /// Notifies the constellation that this frame has received focus.
     Focus,
     /// Forward an event that was sent to the parent window.