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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3 files changed, 9 insertions, 10 deletions

diff --git a/components/script/dom/webgl_extensions/ext/oesvertexarrayobject.rs b/components/script/dom/webgl_extensions/ext/oesvertexarrayobject.rs
index 097742f5441..48385a3d50f 100644
--- a/components/script/dom/webgl_extensions/ext/oesvertexarrayobject.rs
+++ b/components/script/dom/webgl_extensions/ext/oesvertexarrayobject.rs
@@ -2,7 +2,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-use canvas_traits::CanvasMsg;
+use canvas_traits::webgl::{webgl_channel, WebGLCommand, WebGLError};
 use dom::bindings::codegen::Bindings::OESVertexArrayObjectBinding::{self, OESVertexArrayObjectMethods};
 use dom::bindings::codegen::Bindings::OESVertexArrayObjectBinding::OESVertexArrayObjectConstants;
 use dom::bindings::js::{JS, MutNullableJS, Root};
@@ -15,7 +15,6 @@ use js::jsapi::JSContext;
 use js::jsval::{JSVal, NullValue};
 use std::iter;
 use super::{WebGLExtension, WebGLExtensions};
-use webrender_api::{self, WebGLCommand, WebGLError};
 
 #[dom_struct]
 pub struct OESVertexArrayObject {
@@ -48,8 +47,8 @@ impl OESVertexArrayObject {
 impl OESVertexArrayObjectMethods for OESVertexArrayObject {
     // https://www.khronos.org/registry/webgl/extensions/OES_vertex_array_object/
     fn CreateVertexArrayOES(&self) -> Option<Root<WebGLVertexArrayObjectOES>> {
-        let (sender, receiver) = webrender_api::channel::msg_channel().unwrap();
-        self.ctx.send_renderer_message(CanvasMsg::WebGL(WebGLCommand::CreateVertexArray(sender)));
+        let (sender, receiver) = webgl_channel().unwrap();
+        self.ctx.send_command(WebGLCommand::CreateVertexArray(sender));
 
         let result = receiver.recv().unwrap();
         result.map(|vao_id| WebGLVertexArrayObjectOES::new(&self.global(), vao_id))
@@ -66,7 +65,7 @@ impl OESVertexArrayObjectMethods for OESVertexArrayObject {
             if let Some(bound_vao) = self.bound_vao.get() {
                 if bound_vao.id() == vao.id() {
                     self.bound_vao.set(None);
-                    self.ctx.send_renderer_message(CanvasMsg::WebGL(WebGLCommand::BindVertexArray(None)));
+                    self.ctx.send_command(WebGLCommand::BindVertexArray(None));
                 }
             }
 
@@ -80,7 +79,7 @@ impl OESVertexArrayObjectMethods for OESVertexArrayObject {
             }
 
             // Delete the vao
-            self.ctx.send_renderer_message(CanvasMsg::WebGL(WebGLCommand::DeleteVertexArray(vao.id())));
+            self.ctx.send_command(WebGLCommand::DeleteVertexArray(vao.id()));
             vao.set_deleted();
         }
     }
@@ -114,7 +113,7 @@ impl OESVertexArrayObjectMethods for OESVertexArrayObject {
                 return;
             }
 
-            self.ctx.send_renderer_message(CanvasMsg::WebGL(WebGLCommand::BindVertexArray(Some(vao.id()))));
+            self.ctx.send_command(WebGLCommand::BindVertexArray(Some(vao.id())));
             vao.set_ever_bound();
             self.bound_vao.set(Some(&vao));
 
@@ -124,7 +123,7 @@ impl OESVertexArrayObjectMethods for OESVertexArrayObject {
             let element_array = vao.bound_buffer_element_array();
             self.ctx.set_bound_buffer_element_array(element_array.as_ref().map(|buffer| &**buffer));
         } else {
-            self.ctx.send_renderer_message(CanvasMsg::WebGL(WebGLCommand::BindVertexArray(None)));
+            self.ctx.send_command(WebGLCommand::BindVertexArray(None));
             self.bound_vao.set(None);
             self.ctx.set_bound_attrib_buffers(iter::empty());
         }
diff --git a/components/script/dom/webgl_extensions/ext/webglvertexarrayobjectoes.rs b/components/script/dom/webgl_extensions/ext/webglvertexarrayobjectoes.rs
index e44b7c9bc42..2fe109cafa6 100644
--- a/components/script/dom/webgl_extensions/ext/webglvertexarrayobjectoes.rs
+++ b/components/script/dom/webgl_extensions/ext/webglvertexarrayobjectoes.rs
@@ -2,6 +2,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
+use canvas_traits::webgl::WebGLVertexArrayId;
 use core::cell::Ref;
 use core::iter::FromIterator;
 use dom::bindings::cell::DOMRefCell;
@@ -15,7 +16,6 @@ use dom::webglobject::WebGLObject;
 use dom_struct::dom_struct;
 use std::cell::Cell;
 use std::collections::HashMap;
-use webrender_api::WebGLVertexArrayId;
 
 #[dom_struct]
 pub struct WebGLVertexArrayObjectOES {
diff --git a/components/script/dom/webgl_extensions/extensions.rs b/components/script/dom/webgl_extensions/extensions.rs
index 28c32dede64..2a780b129ff 100644
--- a/components/script/dom/webgl_extensions/extensions.rs
+++ b/components/script/dom/webgl_extensions/extensions.rs
@@ -2,6 +2,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
+use canvas_traits::webgl::WebGLError;
 use core::iter::FromIterator;
 use core::nonzero::NonZero;
 use dom::bindings::cell::DOMRefCell;
@@ -19,7 +20,6 @@ use std::cell::Ref;
 use std::collections::{HashMap, HashSet};
 use super::{ext, WebGLExtension};
 use super::wrapper::{WebGLExtensionWrapper, TypedWebGLExtensionWrapper};
-use webrender_api::WebGLError;
 
 // Data types that are implemented for texImage2D and texSubImage2D in WebGLRenderingContext
 // but must trigger a InvalidValue error until the related WebGL Extensions are enabled.