Auto merge of #6812 - ecoal95:webgl-fail, r=jdm

webgl: Make context creation fallible. Fixes #6806



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components/compositing/constellation.rs

@@ -949,12 +949,17 @@ impl<LTF: LayoutTaskFactory, STF: ScriptTaskFactory> Constellation<LTF, STF> {
             &mut self,
             size: &Size2D<i32>,
             attributes: GLContextAttributes,
-            response_sender: IpcSender<(IpcSender<CanvasMsg>, usize)>) {
+            response_sender: IpcSender<Result<(IpcSender<CanvasMsg>, usize), String>>) {
+        let response = match WebGLPaintTask::start(*size, attributes) {
+            Ok((out_of_process_sender, in_process_sender)) => {
                 let id = self.webgl_paint_tasks.len();
-        let (out_of_process_sender, in_process_sender) =
-            WebGLPaintTask::start(*size, attributes).unwrap();
                 self.webgl_paint_tasks.push(in_process_sender);
-        response_sender.send((out_of_process_sender, id)).unwrap()
+                Ok((out_of_process_sender, id))
+            },
+            Err(msg) => Err(msg.to_owned()),
+        };
+
+        response_sender.send(response).unwrap()
     }
 
     fn handle_webdriver_msg(&mut self, msg: WebDriverCommandMsg) {

components/msg/constellation_msg.rs

@@ -268,7 +268,7 @@ pub enum Msg {
     /// WebGL uses the GPU and we don't want to give untrusted content access to the GPU.)
     CreateWebGLPaintTask(Size2D<i32>,
                          GLContextAttributes,
-                         IpcSender<(IpcSender<CanvasMsg>, usize)>),
+                         IpcSender<Result<(IpcSender<CanvasMsg>, usize), String>>),
 }
 
 #[derive(Clone, Eq, PartialEq, Deserialize, Serialize)]

components/script/dom/webglrenderingcontext.rs

@@ -64,20 +64,23 @@ impl WebGLRenderingContext {
                      canvas: &HTMLCanvasElement,
                      size: Size2D<i32>,
                      attrs: GLContextAttributes)
-                     -> Result<WebGLRenderingContext, &'static str> {
+                     -> Result<WebGLRenderingContext, String> {
         let (sender, receiver) = ipc::channel().unwrap();
         let constellation_chan = global.constellation_chan();
         constellation_chan.0
                           .send(ConstellationMsg::CreateWebGLPaintTask(size, attrs, sender))
                           .unwrap();
-        let (ipc_renderer, renderer_id) = receiver.recv().unwrap();
-        Ok(WebGLRenderingContext {
+        let result = receiver.recv().unwrap();
+
+        result.map(|(ipc_renderer, renderer_id)| {
+            WebGLRenderingContext {
                 reflector_: Reflector::new(),
                 global: GlobalField::from_rooted(&global),
                 renderer_id: renderer_id,
                 ipc_renderer: ipc_renderer,
                 last_error: Cell::new(None),
                 canvas: JS::from_ref(canvas),
+            }
         })
     }