Move GIF decoder's aggressive purge into ImageDecoder

third_party/WebKit/Source/platform/image-decoders/gif/GIFImageDecoder.h

 /*
  * Copyright (C) 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 74 matching lines @@
   void parse(GIFParseQuery);
 
   // Called to initialize the frame buffer with the given index, based on
   // the previous frame's disposal method. Returns true on success. On
   // failure, this will mark the image as failed.
   bool initFrameBuffer(size_t frameIndex);
 
   // Like clearCacheExceptFrame(), but preserves two frames instead of one.
   size_t clearCacheExceptTwoFrames(size_t, size_t);
 
-  void updateAggressivePurging(size_t index);
-
   bool m_currentBufferSawAlpha;
-  bool m_purgeAggressively;
   mutable int m_repetitionCount;
   std::unique_ptr<GIFImageReader> m_reader;
 };
 
 }  // namespace blink
 
 #endif