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, 10 insertions, 14 deletions

diff --git a/components/script/dom/webglrenderbuffer.rs b/components/script/dom/webglrenderbuffer.rs
index 03589365c43..9a855651cc9 100644
--- a/components/script/dom/webglrenderbuffer.rs
+++ b/components/script/dom/webglrenderbuffer.rs
@@ -3,7 +3,7 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 // https://www.khronos.org/registry/webgl/specs/latest/1.0/webgl.idl
-use canvas_traits::CanvasMsg;
+use canvas_traits::webgl::{webgl_channel, WebGLCommand, WebGLError, WebGLMsgSender, WebGLRenderbufferId, WebGLResult};
 use dom::bindings::codegen::Bindings::WebGLRenderbufferBinding;
 use dom::bindings::codegen::Bindings::WebGLRenderingContextBinding::WebGLRenderingContextConstants as constants;
 use dom::bindings::js::Root;
@@ -11,10 +11,7 @@ use dom::bindings::reflector::reflect_dom_object;
 use dom::webglobject::WebGLObject;
 use dom::window::Window;
 use dom_struct::dom_struct;
-use ipc_channel::ipc::IpcSender;
 use std::cell::Cell;
-use webrender_api;
-use webrender_api::{WebGLCommand, WebGLRenderbufferId, WebGLResult, WebGLError};
 
 #[dom_struct]
 pub struct WebGLRenderbuffer {
@@ -25,11 +22,11 @@ pub struct WebGLRenderbuffer {
     size: Cell<Option<(i32, i32)>>,
     internal_format: Cell<Option<u32>>,
     #[ignore_heap_size_of = "Defined in ipc-channel"]
-    renderer: IpcSender<CanvasMsg>,
+    renderer: WebGLMsgSender,
 }
 
 impl WebGLRenderbuffer {
-    fn new_inherited(renderer: IpcSender<CanvasMsg>,
+    fn new_inherited(renderer: WebGLMsgSender,
                      id: WebGLRenderbufferId)
                      -> WebGLRenderbuffer {
         WebGLRenderbuffer {
@@ -43,17 +40,17 @@ impl WebGLRenderbuffer {
         }
     }
 
-    pub fn maybe_new(window: &Window, renderer: IpcSender<CanvasMsg>)
+    pub fn maybe_new(window: &Window, renderer: WebGLMsgSender)
                      -> Option<Root<WebGLRenderbuffer>> {
-        let (sender, receiver) = webrender_api::channel::msg_channel().unwrap();
-        renderer.send(CanvasMsg::WebGL(WebGLCommand::CreateRenderbuffer(sender))).unwrap();
+        let (sender, receiver) = webgl_channel().unwrap();
+        renderer.send(WebGLCommand::CreateRenderbuffer(sender)).unwrap();
 
         let result = receiver.recv().unwrap();
         result.map(|renderbuffer_id| WebGLRenderbuffer::new(window, renderer, renderbuffer_id))
     }
 
     pub fn new(window: &Window,
-               renderer: IpcSender<CanvasMsg>,
+               renderer: WebGLMsgSender,
                id: WebGLRenderbufferId)
                -> Root<WebGLRenderbuffer> {
         reflect_dom_object(box WebGLRenderbuffer::new_inherited(renderer, id),
@@ -74,14 +71,14 @@ impl WebGLRenderbuffer {
 
     pub fn bind(&self, target: u32) {
         self.ever_bound.set(true);
-        let msg = CanvasMsg::WebGL(WebGLCommand::BindRenderbuffer(target, Some(self.id)));
+        let msg = WebGLCommand::BindRenderbuffer(target, Some(self.id));
         self.renderer.send(msg).unwrap();
     }
 
     pub fn delete(&self) {
         if !self.is_deleted.get() {
             self.is_deleted.set(true);
-            let _ = self.renderer.send(CanvasMsg::WebGL(WebGLCommand::DeleteRenderbuffer(self.id)));
+            let _ = self.renderer.send(WebGLCommand::DeleteRenderbuffer(self.id));
         }
     }
 
@@ -110,8 +107,7 @@ impl WebGLRenderbuffer {
 
         // FIXME: Invalidate completeness after the call
 
-        let msg = CanvasMsg::WebGL(WebGLCommand::RenderbufferStorage(constants::RENDERBUFFER,
-                                                                     internal_format, width, height));
+        let msg = WebGLCommand::RenderbufferStorage(constants::RENDERBUFFER, internal_format, width, height);
         self.renderer.send(msg).unwrap();
 
         self.size.set(Some((width, height)));