GIF Animations "clear from cache related glitch" fix

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 62 matching lines @@
     void decode(size_t) override;
 
     // Parses as much as is needed to answer the query, ignoring bitmap
     // data. If parsing fails, sets the "decode failure" flag.
     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);
+    // If disposal method is DisposeOverwritePrevious, keep two frames: current

[Peter Kasting, 2016/01/14 00:17:29]

Nit: Blank line above this

[aleksandar.stojiljkovic, 2016/01/14 11:32:53]

Done.

+    // and it's required previous frame.

[Peter Kasting, 2016/01/14 00:17:29]

This comment is technically a bit of a layering violation, because this
describes how callers are using this rather than how the function actually
works.  I would do this:

  // Like clearCacheExceptFrame(), but preserves two frames instead of one.
  size_t clearCacheExceptFrames(size_t frame1, size_t frame2);

[aleksandar.stojiljkovic, 2016/01/14 11:32:53]

Done.

+    size_t clearCacheExceptTwoFrames(size_t dontClearFrame1, size_t dontClearFrame2);
 
     bool m_currentBufferSawAlpha;
     mutable int m_repetitionCount;
     OwnPtr<GIFImageReader> m_reader;
 };
 
 } // namespace blink
 
 #endif