Merge 116587 - [chromium] Don't draw when canDraw() is false

Source/WebCore/platform/graphics/chromium/cc/CCSingleThreadProxy.cpp

 /*
  * Copyright (C) 2011 Google 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 307 matching lines @@
     return doComposite();
 }
 
 bool CCSingleThreadProxy::doComposite()
 {
     ASSERT(!m_contextLost);
     {
       DebugScopedSetImplThread impl;
       double monotonicTime = monotonicallyIncreasingTime();
       double wallClockTime = currentTime();
+      m_layerTreeHostImpl->animate(monotonicTime, wallClockTime);
 
-      m_layerTreeHostImpl->animate(monotonicTime, wallClockTime);
+      // We guard prepareToDraw() with canDraw() because it always returns a valid frame, so can only
+      // be used when such a frame is possible. Since drawLayers() depends on the result of
+      // prepareToDraw(), it is guarded on canDraw() as well.
+      if (!m_layerTreeHostImpl->canDraw())
+          return false;
+
       CCLayerTreeHostImpl::FrameData frame;
       m_layerTreeHostImpl->prepareToDraw(frame);
       m_layerTreeHostImpl->drawLayers(frame);
       m_layerTreeHostImpl->didDrawAllLayers(frame);
     }
 
     if (m_layerTreeHostImpl->isContextLost()) {
         m_contextLost = true;
         m_layerTreeHost->didLoseContext();
         return false;
     }
 
     return true;
 }
 
 void CCSingleThreadProxy::didSwapFrame()
 {
     if (m_nextFrameIsNewlyCommittedFrame) {
         m_nextFrameIsNewlyCommittedFrame = false;
         m_layerTreeHost->didCommitAndDrawFrame();
     }
 }
 
 }