Auto merge of #17891 - MortimerGoro:webgl_move, r=glennw,emilio

Improved WebGL architecture

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Info about the big picture and the goals of the WebGL refactor in this thread: https://groups.google.com/forum/#!topic/mozilla.dev.servo/0WMGz60kKzQ

I tried to reduce this PR as much as possible as requested in the thread. I'll do separate PRs for other features (e.g.: Batch messages or use shared memory to improve frame times) or fixes.

Some tips to ease the review process:
- Most changes in DOM objects follow the same pattern (remove CanvasMsg wrapper and use the new sender method).
- WebGLCommands are the same ones as before (moved from webrender_api). So those lines are already reviewed.
- See WebGL traits in [components/canvas_traits/webgl.rs](https://github.com/servo/servo/pull/17891/files#diff-8701045d01505418701d0631d4d45562)
- See WebGLThread and WR External Image bridge in [components/canvas/webgl_thread.rs](https://github.com/servo/servo/pull/17891/files#diff-281554879f39a2a041f7a69d442a5d2e)
- The implementation submitted in this PR creates a single `WebGLThread` for all ScriptThread/Pipelines. See that in [components/canvas/webgl_mode/inprocess.rs](https://github.com/servo/servo/pull/17891/files#diff-250070c6c5a38c7f9fa0f5b3c101f68b)

The conformance tests will help to guarantee that we don't miss anything.

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- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [ ] These changes fix #__ (github issue number if applicable).

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

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1 files changed, 5 insertions, 11 deletions

diff --git a/components/canvas/canvas_paint_thread.rs b/components/canvas/canvas_paint_thread.rs
index b7e21777001..8fe05d1f6a9 100644
--- a/components/canvas/canvas_paint_thread.rs
+++ b/components/canvas/canvas_paint_thread.rs
@@ -8,7 +8,7 @@ use azure::azure_hl::{BackendType, DrawOptions, DrawTarget, Pattern, StrokeOptio
 use azure::azure_hl::{Color, ColorPattern, DrawSurfaceOptions, Filter, PathBuilder};
 use azure::azure_hl::{ExtendMode, GradientStop, LinearGradientPattern, RadialGradientPattern};
 use azure::azure_hl::SurfacePattern;
-use canvas_traits::*;
+use canvas_traits::canvas::*;
 use cssparser::RGBA;
 use euclid::{Transform2D, Point2D, Vector2D, Rect, Size2D};
 use ipc_channel::ipc::{self, IpcSender};
@@ -193,12 +193,8 @@ impl<'a> CanvasPaintThread<'a> {
                             Canvas2dMsg::SetShadowColor(ref color) => painter.set_shadow_color(color.to_azure_style()),
                         }
                     },
-                    CanvasMsg::Common(message) => {
-                        match message {
-                            CanvasCommonMsg::Close => break,
-                            CanvasCommonMsg::Recreate(size) => painter.recreate(size),
-                        }
-                    },
+                    CanvasMsg::Close => break,
+                    CanvasMsg::Recreate(size) => painter.recreate(size),
                     CanvasMsg::FromScript(message) => {
                         match message {
                             FromScriptMsg::SendPixels(chan) => {
@@ -213,8 +209,6 @@ impl<'a> CanvasPaintThread<'a> {
                             }
                         }
                     }
-                    CanvasMsg::WebGL(_) => panic!("Wrong WebGL message sent to Canvas2D thread"),
-                    CanvasMsg::WebVR(_) => panic!("Wrong WebVR message sent to Canvas2D thread"),
                 }
             }
         }).expect("Thread spawning failed");
@@ -571,7 +565,7 @@ impl<'a> CanvasPaintThread<'a> {
         })
     }
 
-    fn send_data(&mut self, chan: IpcSender<CanvasData>) {
+    fn send_data(&mut self, chan: IpcSender<CanvasImageData>) {
         self.drawtarget.snapshot().get_data_surface().with_data(|element| {
             let size = self.drawtarget.get_size();
 
@@ -614,7 +608,7 @@ impl<'a> CanvasPaintThread<'a> {
             let data = CanvasImageData {
                 image_key: self.image_key.unwrap(),
             };
-            chan.send(CanvasData::Image(data)).unwrap();
+            chan.send(data).unwrap();
         })
     }