Implement offscreenCanvas.getContext('webgl') on a worker thread

third_party/WebKit/LayoutTests/fast/canvas/OffscreenCanvas-getContext-in-worker.html

Index: third_party/WebKit/LayoutTests/fast/canvas/OffscreenCanvas-getContext-in-worker.html
diff --git a/third_party/WebKit/LayoutTests/fast/canvas/OffscreenCanvas-getContext-in-worker.html b/third_party/WebKit/LayoutTests/fast/canvas/OffscreenCanvas-getContext-in-worker.html
index 91a3fd01f4d86616ba74f92378d00a878319f1a3..0838947b67235c2df4c071f2d09305950eaeac58 100644
--- a/third_party/WebKit/LayoutTests/fast/canvas/OffscreenCanvas-getContext-in-worker.html
+++ b/third_party/WebKit/LayoutTests/fast/canvas/OffscreenCanvas-getContext-in-worker.html
@@ -8,12 +8,11 @@ self.onmessage = function(e) {
     var bCanvas = new OffscreenCanvas(50, 50);
     try {
       var ctx1 = aCanvas.getContext('2d');
-      //TODO(crbug.com/602391): implement get webgl context in worker
       var ctx2 = bCanvas.getContext('webgl');
-      if (toString.call(ctx1) != '[object OffscreenCanvasRenderingContext2D]') {
-          self.postMessage("aCanvas.getContext('2d') does not return [object OffscreenCanvasRenderingContext2D]");
-      } else if (toString.call(ctx2) != '[object Null]') {
-          self.postMessage("bCanvas.getContext('webgl') does not return [object Null]");
+      if (!(ctx1 instanceof OffscreenCanvasRenderingContext2D)) {

[Ken Russell (switch to Gerrit), 2016/05/09 18:00:13]

Note: OffscreenCanvasRenderingContext2D is not part of any of the current WHATWG
specs or proposals. Either it needs to be specified, or this test needs to be
changed to refer to CanvasRenderingContext2D, and the problematic methods on
CanvasRenderingContext2D need to be specified to throw exceptions, or similar.

[xidachen, 2016/05/09 18:18:20]

Agreed. I believe junov@ is currently in the process of making
OffscreenCanvasRenderingContext2D as an official spec. I will commit this CL as
what is now and come back to this issue later.

+          self.postMessage("aCanvas.getContext('2d') returns " + ctx1);
+      } else if (!(ctx2 instanceof WebGLRenderingContext)) {
+          self.postMessage("bCanvas.getContext('webgl') returns " + ctx2);
       } else {
           self.postMessage("success");
       }
@@ -25,7 +24,7 @@ self.onmessage = function(e) {
 
 <script>
 jsTestIsAsync = true;
-description("Tests that the 2D context of OffscreenCanvas can be constructed on a worker thread.");
+description("Tests that the 2D and webgl context of OffscreenCanvas can be constructed on a worker thread.");
 
 function makeWorker(script) {
   var blob = new Blob([script]);
@@ -35,7 +34,7 @@ function makeWorker(script) {
 function handleMessageFromWorker(msg)
 {
     if (msg.data == "success") {
-        testPassed("getContext('2d') correctly returns [object OffscreenCanvasRenderingContext2D].");
+        testPassed("getContext('2d') and getContext('webgl') works on a worker thread");
     } else {
         testFailed(msg.data);
     }