Fix missing finalizeFrame barriers in WebGL animations

third_party/WebKit/Source/core/html/canvas/CanvasRenderingContext.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 148 matching lines @@
 void CanvasRenderingContext::didProcessTask() {
   Platform::current()->currentThread()->removeTaskObserver(this);
   m_finalizeFrameScheduled = false;
 
   if (!canvas())
     return;
 
   // The end of a script task that drew content to the canvas is the point
   // at which the current frame may be considered complete.
   canvas()->finalizeFrame();
+  finalizeFrame();

[Ken Russell (switch to Gerrit), 2017/02/18 00:08:01]

Why is this being added here instead of inside HTMLCanvasElement::finalizeFrame?
It seems oddly placed.

[Justin Novosad, 2017/02/21 18:06:21]

Because not all rendering contexts have an HTMLCanvasElement.  They may have an
OffscreenCanvas.

[Ken Russell (switch to Gerrit), 2017/02/21 19:23:10]

Ah right. Thanks.

[xlai (Olivia), 2017/02/21 19:56:56]

What would be the scenarios when finalizeFrame() is called for OffscreenCanvas?
Do you think it's ready to add an extra test for OffscreenCanvas in this CL or
there needs to be more refactoring
in the code (probably follow-up CLs) that handles those scenarios?

 }
 
 CanvasRenderingContext::ContextType CanvasRenderingContext::contextTypeFromId(
     const String& id) {
   if (id == "2d")
     return Context2d;
   if (id == "experimental-webgl")
     return ContextExperimentalWebgl;
   if (id == "webgl")
     return ContextWebgl;
@@ skipping 42 matching lines @@
   }
   return taintOrigin;
 }
 
 DEFINE_TRACE(CanvasRenderingContext) {
   visitor->trace(m_canvas);
   visitor->trace(m_offscreenCanvas);
 }
 
 }  // namespace blink