Speculative fix for crash in Canvas2DLayerBridge::freeReleasedMailbox

Source/platform/graphics/Canvas2DImageBufferSurface.h

 /*
  * Copyright (C) 2013 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 37 matching lines @@
 
     virtual ~Canvas2DImageBufferSurface()
     {
         if (m_layerBridge)
             m_layerBridge->beginDestruction();
     }
 
     // ImageBufferSurface implementation
     virtual void willUse() OVERRIDE { m_layerBridge->willUse(); }
     virtual SkCanvas* canvas() const OVERRIDE { return m_layerBridge->canvas(); }
-    virtual bool isValid() const OVERRIDE { return m_layerBridge && m_layerBridge->isValid(); }
+    virtual bool isValid() const OVERRIDE { return m_layerBridge && (m_layerBridge->isValid() || m_layerBridge->tryRecover()); }

[Stephen White, 2014/03/04 15:27:41]

<bikeshed>"tryRecover()" is a bit awkward. Maybe "recoverContext()"?</bikeshed>

     virtual blink::WebLayer* layer() const OVERRIDE { return m_layerBridge->layer(); }
     virtual Platform3DObject getBackingTexture() const OVERRIDE { return m_layerBridge->getBackingTexture(); }
     virtual bool isAccelerated() const OVERRIDE { return m_layerBridge->isAccelerated(); }
     virtual void setIsHidden(bool hidden) OVERRIDE { m_layerBridge->setIsHidden(hidden); }
 
 private:
     RefPtr<Canvas2DLayerBridge> m_layerBridge;
 };
 
 }
 
 #endif