Don't cache any SkBitmaps in DeferredImageDecoder

Source/platform/graphics/ImageSource.h

 /*
  * Copyright (C) 2004, 2005, 2006 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 23 matching lines @@
 
 namespace blink {
 
 class DeferredImageDecoder;
 class ImageOrientation;
 class IntPoint;
 class IntSize;
 class NativeImageSkia;
 class SharedBuffer;
 
-// GIF and WebP support animation. The explanation below is in terms of GIF,
-// but the same constants are used for WebP, too.
-// GIFs have an optional 16-bit unsigned loop count that describes how an
-// animated GIF should be cycled.  If the loop count is absent, the animation
-// cycles once; if it is 0, the animation cycles infinitely; otherwise the
-// animation plays n + 1 cycles (where n is the specified loop count).  If the
-// GIF decoder defaults to cAnimationLoopOnce in the absence of any loop count
-// and translates an explicit "0" loop count to cAnimationLoopInfinite, then we
-// get a couple of nice side effects:
-//   * By making cAnimationLoopOnce be 0, we allow the animation cycling code in
-//     BitmapImage.cpp to avoid special-casing it, and simply treat all
-//     non-negative loop counts identically.
-//   * By making the other two constants negative, we avoid conflicts with any
-//     real loop count values.
-const int cAnimationLoopOnce = 0;
-const int cAnimationLoopInfinite = -1;
-const int cAnimationNone = -2;
-
+// This is a helper class used by BitmapImage only. If you need an image
+// decoder then you should look into
+// Source/platform/image-decoders/ImageDecoder.h.
 class PLATFORM_EXPORT ImageSource {
     WTF_MAKE_NONCOPYABLE(ImageSource);
 public:
     enum AlphaOption {
         AlphaPremultiplied,
         AlphaNotPremultiplied
     };
 
     enum GammaAndColorProfileOption {
         GammaAndColorProfileApplied,
@@ skipping 16 matching lines @@
     // earlier frame may require more work to be done, e.g. redecoding the image
     // from the beginning.
     //
     // Implementations may elect to preserve more frames than the one requested
     // here if doing so is likely to save CPU time in the future, but will pay
     // an increased memory cost to do so.
     //
     // Returns the number of bytes of frame data actually cleared.
     size_t clearCacheExceptFrame(size_t);
 
-    bool initialized() const;
-    void resetDecoder();
-
     void setData(SharedBuffer& data, bool allDataReceived);
     String filenameExtension() const;
 
     bool isSizeAvailable();
     bool hasColorProfile() const;
     IntSize size(RespectImageOrientationEnum = DoNotRespectImageOrientation) const;
     IntSize frameSizeAtIndex(size_t, RespectImageOrientationEnum = DoNotRespectImageOrientation) const;
 
     bool getHotSpot(IntPoint&) const;
-
-    // Returns one of the cAnimationXXX constants at the top of the file, or
-    // a loop count. In the latter case, the actual number of times the animation
-    // cycles is one more than the loop count. See comment atop the file.
     int repetitionCount();
 
     size_t frameCount() const;
 
     PassRefPtr<NativeImageSkia> createFrameAtIndex(size_t);
 
     float frameDurationAtIndex(size_t) const;
     bool frameHasAlphaAtIndex(size_t) const; // Whether or not the frame actually used any alpha.
     bool frameIsCompleteAtIndex(size_t) const; // Whether or not the frame is fully received.
     ImageOrientation orientationAtIndex(size_t) const; // EXIF image orientation
 
     // Return the number of bytes in the decoded frame. If the frame is not yet
     // decoded then return 0.
     unsigned frameBytesAtIndex(size_t) const;
 
 private:
     OwnPtr<DeferredImageDecoder> m_decoder;
 
     AlphaOption m_alphaOption;
     GammaAndColorProfileOption m_gammaAndColorProfileOption;
 };
 
 } // namespace blink
 
 #endif