Teach Skia to use discardable memory

Source/platform/graphics/DeferredImageDecoder.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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 34 matching lines @@
     WTF_MAKE_NONCOPYABLE(DeferredImageDecoder);
 public:
     ~DeferredImageDecoder();
     static PassOwnPtr<DeferredImageDecoder> create(const SharedBuffer& data, ImageSource::AlphaOption, ImageSource::GammaAndColorProfileOption);
 
     static PassOwnPtr<DeferredImageDecoder> createForTesting(PassOwnPtr<ImageDecoder>);
 
     static bool isLazyDecoded(const SkBitmap&);
 
     static void setEnabled(bool);
+    static void setSkiaDiscardableMemoryEnabled(bool);
 
     String filenameExtension() const;
 
     ImageFrame* frameBufferAtIndex(size_t index);
 
     void setData(SharedBuffer* data, bool allDataReceived);
 
     bool isSizeAvailable();
     IntSize size() const;
     IntSize frameSizeAtIndex(size_t index) const;
     size_t frameCount();
     int repetitionCount() const;
     size_t clearCacheExceptFrame(size_t);
     bool frameHasAlphaAtIndex(size_t index) const;
     bool frameIsCompleteAtIndex(size_t) const;
     float frameDurationAtIndex(size_t) const;
     unsigned frameBytesAtIndex(size_t index) const;
     ImageOrientation orientation() const;
     bool hotSpot(IntPoint&) const;
 
     // For testing.
     ImageFrameGenerator* frameGenerator() { return m_frameGenerator.get(); }
 
 private:
     explicit DeferredImageDecoder(PassOwnPtr<ImageDecoder> actualDecoder);
     void prepareLazyDecodedFrames();
+    SkBitmap createBitmap(size_t index);
+    SkBitmap createSkiaDiscardableBitmap(size_t index);
     SkBitmap createLazyDecodingBitmap(size_t index);
     void activateLazyDecoding();
     void setData(PassRefPtr<SharedBuffer>, bool allDataReceived);
 
     RefPtr<SharedBuffer> m_data;
     bool m_allDataReceived;
     OwnPtr<ImageDecoder> m_actualDecoder;
 
     String m_filenameExtension;
     IntSize m_size;
     ImageOrientation m_orientation;
     int m_repetitionCount;
 
     Vector<OwnPtr<ImageFrame> > m_lazyDecodedFrames;
     RefPtr<ImageFrameGenerator> m_frameGenerator;
 
     static bool s_enabled;
+    static bool s_skiaDiscardableMemoryEnabled;
 };
 
 } // namespace WebCore
 
 #endif