Implementation of 2D canvas context lost/restored events

Source/platform/graphics/ImageBufferSurface.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 26 matching lines @@
 #include "wtf/FastAllocBase.h"
 #include "wtf/Noncopyable.h"
 
 class SkCanvas;
 class SkBitmap;
 
 namespace blink { class WebLayer; }
 
 namespace WebCore {
 
+class ImageBuffer;
+
 enum OpacityMode {
     NonOpaque,
     Opaque,
 };
 
 class PLATFORM_EXPORT ImageBufferSurface {
     WTF_MAKE_NONCOPYABLE(ImageBufferSurface); WTF_MAKE_FAST_ALLOCATED;
 public:
     virtual ~ImageBufferSurface() { }
 
     virtual SkCanvas* canvas() const = 0;
     virtual const SkBitmap& bitmap() const;
     virtual void willUse() { } // Called by ImageBuffer before reading or writing to the surface.
     virtual bool isValid() const = 0;
+    virtual bool restore() { return false; };
     virtual blink::WebLayer* layer() const { return 0; };
     virtual bool isAccelerated() const { return false; }
     virtual Platform3DObject getBackingTexture() const { return 0; }
     virtual bool cachedBitmapEnabled() const { return false; }
     virtual const SkBitmap& cachedBitmap() const;
     virtual void invalidateCachedBitmap() { }
     virtual void updateCachedBitmapIfNeeded() { }
     virtual void setIsHidden(bool) { }
+    virtual void setImageBuffer(ImageBuffer*) { }
 
     OpacityMode opacityMode() const { return m_opacityMode; }
     const IntSize& size() const { return m_size; }
+    void notifyIsValidChanged(bool isValid) const;
 
 protected:
+    ImageBufferSurface(const IntSize&, OpacityMode);
     void clear();
 
-    ImageBufferSurface(const IntSize& size, OpacityMode opacityMode)
-        : m_opacityMode(opacityMode)
-        , m_size(size)
-    {
-        setIsHidden(false);
-    }
-
 private:
     OpacityMode m_opacityMode;
     IntSize m_size;
 };
 
 } // namespace WebCore
 
 #endif