Submit CompositorFrame from worker

third_party/WebKit/Source/modules/offscreencanvas2d/OffscreenCanvasRenderingContext2D.cpp

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "modules/offscreencanvas2d/OffscreenCanvasRenderingContext2D.h"
 
 #include "bindings/modules/v8/OffscreenCanvasRenderingContext2DOrWebGLRenderingContextOrWebGL2RenderingContext.h"
 #include "core/frame/ImageBitmap.h"
 #include "core/frame/Settings.h"
 #include "core/workers/WorkerGlobalScope.h"
@@ skipping 26 matching lines @@
     if (workerSettings && workerSettings->disableReadingFromCanvas())
         canvas->setDisableReadingFromCanvasTrue();
 }
 
 DEFINE_TRACE(OffscreenCanvasRenderingContext2D)
 {
     CanvasRenderingContext::trace(visitor);
     BaseRenderingContext2D::trace(visitor);
 }
 
-void OffscreenCanvasRenderingContext2D::commit(ExecutionContext* executionContext)
+void OffscreenCanvasRenderingContext2D::commit(ExceptionState& exceptionState)
 {
-    if (executionContext->isWorkerGlobalScope()) {
-        // TODO(xlai): implement commit() on worker thread; currently, do
-        // nothing for worker thread. See crbug.com/563858.
-        return;
+    if (getOffscreenCanvas()->getAssociatedCanvasId() < 0) {
+        // If an OffscreenCanvas has no associated canvas Id, it indicates that
+        // it is not an OffscreenCanvas created by transfering control from html
+        // canvas.
+        exceptionState.throwDOMException(InvalidStateError, "Commit() has no effect if HTMLCanvasElement.transferControlToOffscreen() is not called.");

[Justin Novosad, 2016/09/07 21:40:15]

This message is not true: there is an effect, an exception is thrown.  I think
the message would be clearer like this: "commit() was called on a context whose
OffscreenCanvas is not associated with an canvas element."

[xlai (Olivia), 2016/09/08 15:27:15]

Done.

     }
     getOffscreenCanvas()->getOrCreateFrameDispatcher()->dispatchFrame();
 }
 
 // BaseRenderingContext2D implementation
 bool OffscreenCanvasRenderingContext2D::originClean() const
 {
     return getOffscreenCanvas()->originClean();
 }
 
@@ skipping 145 matching lines @@
 bool OffscreenCanvasRenderingContext2D::isContextLost() const
 {
     return false;
 }
 
 bool OffscreenCanvasRenderingContext2D::isPaintable() const
 {
     return this->imageBuffer();
 }
 }