Decode GIF image frames on demand.

Source/core/platform/graphics/GeneratedImage.h

 /*
  * Copyright (C) 2008 Apple Computer, 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 28 matching lines @@
 
     virtual void setContainerSize(const IntSize& size) { m_size = size; }
     virtual bool usesContainerSize() const { return true; }
     virtual bool hasRelativeWidth() const { return true; }
     virtual bool hasRelativeHeight() const { return true; }
     virtual void computeIntrinsicDimensions(Length& intrinsicWidth, Length& intrinsicHeight, FloatSize& intrinsicRatio);
 
     virtual IntSize size() const { return m_size; }
 
     // Assume that generated content has no decoded data we need to worry about
-    virtual void destroyDecodedData(bool /*destroyAll*/ = true) { }
+    virtual void destroyDecodedData() OVERRIDE { }
     virtual unsigned decodedSize() const { return 0; }
 
     virtual void reportMemoryUsage(MemoryObjectInfo*) const OVERRIDE;
 
 protected:
     virtual void draw(GraphicsContext*, const FloatRect& dstRect, const FloatRect& srcRect, ColorSpace styleColorSpace, CompositeOperator, BlendMode) = 0;
     virtual void drawPattern(GraphicsContext*, const FloatRect& srcRect, const AffineTransform& patternTransform,
         const FloatPoint& phase, ColorSpace styleColorSpace, CompositeOperator, const FloatRect& destRect, BlendMode) = 0;
 
     // FIXME: Implement this to be less conservative.
     virtual bool currentFrameKnownToBeOpaque() OVERRIDE { return false; }
 
     GeneratedImage() { }
 
     IntSize m_size;
 };
 
 }
 
 #endif