Teach Skia to use discardable memory

Source/platform/graphics/ImageFrameGenerator.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 48 matching lines @@
     static PassRefPtr<ImageFrameGenerator> create(const SkISize& fullSize, PassRefPtr<SharedBuffer> data, bool allDataReceived, bool isMultiFrame = false)
     {
         return adoptRef(new ImageFrameGenerator(fullSize, data, allDataReceived, isMultiFrame));
     }
 
     ImageFrameGenerator(const SkISize& fullSize, PassRefPtr<SharedBuffer>, bool allDataReceived, bool isMultiFrame);
     ~ImageFrameGenerator();
 
     const ScaledImageFragment* decodeAndScale(const SkISize& scaledSize, size_t index = 0);
 
+    // Decodes and scales the specified frame indicated by |index|. Dimensions
+    // and output format are specified in |info|. Decoded pixels are written
+    // into |pixels| with a stride of |rowBytes|.
+    //
+    // Returns true if decoding was successful.
+    bool decodeAndScale(const SkImageInfo&, size_t index, void* pixels, size_t rowBytes);
+
     void setData(PassRefPtr<SharedBuffer>, bool allDataReceived);
 
     // Creates a new SharedBuffer containing the data received so far.
     void copyData(RefPtr<SharedBuffer>*, bool* allDataReceived);
 
     SkISize getFullSize() const { return m_fullSize; }
 
     bool isMultiFrame() const { return m_isMultiFrame; }
 
     // FIXME: Return alpha state for each frame.
@@ skipping 34 matching lines @@
     // Prevents multiple decode operations on the same data.
     Mutex m_decodeMutex;
 
     // Protect concurrent access to m_hasAlpha.
     Mutex m_alphaMutex;
 };
 
 } // namespace WebCore
 
 #endif