Implement WebGL's commit on the main thread

third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp

 /*
  * Copyright (C) 2009 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 631 matching lines @@
     shouldFailContextCreationForTesting = true;
 }
 
 ImageBitmap* WebGLRenderingContextBase::transferToImageBitmapBase()
 {
     if (!drawingBuffer())
         return nullptr;
     return ImageBitmap::create(drawingBuffer()->transferToStaticBitmapImage());
 }
 
+void WebGLRenderingContextBase::commit(ExceptionState& exceptionState)
+{
+    if (!getOffscreenCanvas()) {
+        exceptionState.throwDOMException(InvalidStateError, "No OffscreenCanvas exist, abort commit().");

[xlai (Olivia), 2016/09/09 20:30:41]

Could you add a sub-test to OffscreenCanvas-commit-invalid-call.html for this
exception msg?

[Ken Russell (switch to Gerrit), 2016/09/09 21:38:17]

Also, nit: exist -> exists

+        return;
+    }
+    // no HTMLCanvas associated, thrown InvalidStateError
+    if (getOffscreenCanvas()->getAssociatedCanvasId() == -1) {
+        exceptionState.throwDOMException(InvalidStateError, "The OffscreenCanvas has no associated HTMLCanvasElement, abort commit().");

[xlai (Olivia), 2016/09/09 20:30:41]

Could you change the exception message to "Commit() was called on a context
whose OffscreenCanvas is not associated with a canvas element."? 
This is to be consistent with the 2d context error msg.

+        return;
+    }
+    if (!drawingBuffer())
+        return;
+    getOffscreenCanvas()->getOrCreateFrameDispatcher()->dispatchFrame(drawingBuffer()->transferToStaticBitmapImage());
+}
+
 PassRefPtr<Image> WebGLRenderingContextBase::getImage(AccelerationHint hint, SnapshotReason reason) const
 {
     if (!drawingBuffer())
         return nullptr;
 
     drawingBuffer()->commit();
     IntSize size = clampedCanvasSize();
     OpacityMode opacityMode = creationAttributes().hasAlpha() ? NonOpaque : Opaque;
     std::unique_ptr<AcceleratedImageBufferSurface> surface = wrapUnique(new AcceleratedImageBufferSurface(size, opacityMode));
     if (!surface->isValid())
@@ skipping 5775 matching lines @@
 
 void WebGLRenderingContextBase::getHTMLOrOffscreenCanvas(HTMLCanvasElementOrOffscreenCanvas& result) const
 {
     if (canvas())
         result.setHTMLCanvasElement(canvas());
     else
         result.setOffscreenCanvas(getOffscreenCanvas());
 }
 
 } // namespace blink