Disable 2D canvas switch to CPU rendering while backgrounded

third_party/WebKit/Source/platform/graphics/Canvas2DLayerBridge.h

 /*
  * Copyright (C) 2012 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
@@ skipping 54 matching lines @@
 // TODO: Find a better fix for crbug.com/588434
 #define CANVAS2D_HIBERNATION_ENABLED 0
 
 // IOSurfaces are a primitive only present on OS X.
 #define USE_IOSURFACE_FOR_2D_CANVAS 1
 #else
 #define CANVAS2D_HIBERNATION_ENABLED 1
 #define USE_IOSURFACE_FOR_2D_CANVAS 0
 #endif
 
+// TODO: Fix background rendering and remove this workaround. crbug.com/600386
+#define CANVAS2D_BACKGROUND_RENDER_SWITCH_TO_CPU 0
+
 class PLATFORM_EXPORT Canvas2DLayerBridge : public WebExternalTextureLayerClient, public WebThread::TaskObserver, public RefCounted<Canvas2DLayerBridge> {
     WTF_MAKE_NONCOPYABLE(Canvas2DLayerBridge);
 public:
     enum AccelerationMode {
         DisableAcceleration,
         EnableAcceleration,
         ForceAccelerationForTesting,
     };
 
     static PassRefPtr<Canvas2DLayerBridge> create(const IntSize&, int msaaSampleCount, OpacityMode, AccelerationMode);
@@ skipping 186 matching lines @@
     // Each element in this vector represents an IOSurface backed texture that
     // is ready to be reused.
     // Elements in this vector can safely be purged in low memory conditions.
     Vector<ImageInfo> m_imageInfoCache;
 #endif // USE_IOSURFACE_FOR_2D_CANVAS
 };
 
 } // namespace blink
 
 #endif