Reland change to enable deferred image decoding for animated GIFs

Source/core/platform/graphics/chromium/LazyDecodingPixelRef.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 14 matching lines @@
 
 #ifndef LazyDecodingPixelRef_h
 #define LazyDecodingPixelRef_h
 
 #include "SkFlattenableBuffers.h"
 #include "SkPixelRef.h"
 #include "SkRect.h"
 #include "SkSize.h"
 #include "SkTypes.h"
 #include "skia/ext/lazy_pixel_ref.h"
+
 #include "wtf/RefPtr.h"
-#include "wtf/ThreadingPrimitives.h"
 
 using skia::LazyPixelRef;
 
 class SkData;
 
 namespace WebCore {
 
 class ImageFrameGenerator;
 class ScaledImageFragment;
 
 class LazyDecodingPixelRef : public LazyPixelRef {
 public:
-    LazyDecodingPixelRef(PassRefPtr<ImageFrameGenerator>, const SkISize& scaledSize, const SkIRect& scaledSubset);
+    LazyDecodingPixelRef(PassRefPtr<ImageFrameGenerator>, const SkISize& scaledSize, size_t index, const SkIRect& scaledSubset);
     virtual ~LazyDecodingPixelRef();
 
     SK_DECLARE_UNFLATTENABLE_OBJECT()
 
     PassRefPtr<ImageFrameGenerator> frameGenerator() const { return m_frameGenerator; }
+    size_t frameIndex() const { return m_frameIndex; }
     bool isScaled(const SkISize& fullSize) const;
     bool isClipped() const;
 
     // Returns true if the image might already be decoded in the cache.
     // Optimistic version of PrepareToDecode; requires less locking.
     virtual bool MaybeDecoded();
     virtual bool PrepareToDecode(const LazyPixelRef::PrepareParams&);
     virtual void Decode();
 
 protected:
     // SkPixelRef implementation.
     virtual void* onLockPixels(SkColorTable**);
     virtual void onUnlockPixels();
     virtual bool onLockPixelsAreWritable() const;
 
     virtual SkData* onRefEncodedData() SK_OVERRIDE;
 
 private:
     RefPtr<ImageFrameGenerator> m_frameGenerator;
+    size_t m_frameIndex;
     SkISize m_scaledSize;
     SkIRect m_scaledSubset;
 
     const ScaledImageFragment* m_lockedCachedImage;
-    Mutex m_mutex;
 };
 
 } // namespace WebCore
 
 #endif // LazyDecodingPixelRef_h_