Add support for Animated PNG

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

 /*
  * 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 171 matching lines @@
 }
 
 bool GIFImageDecoder::parseCompleted() const {
   return m_reader && m_reader->parseCompleted();
 }
 
 bool GIFImageDecoder::frameComplete(size_t frameIndex) {
   // Initialize the frame if necessary.  Some GIFs insert do-nothing frames,
   // in which case we never reach haveDecodedRow() before getting here.
   if (!initFrameBuffer(frameIndex))
-    return false;  // initFrameBuffer() has already called setFailed().
+    return setFailed();
+
+  if (!m_currentBufferSawAlpha)
+    correctAlphaWhenFrameBufferSawNoAlpha(frameIndex);

[Noel Gordon, 2017/03/08 16:26:14]

Nod.

 
   m_frameBufferCache[frameIndex].setStatus(ImageFrame::FrameComplete);
-  if (!m_currentBufferSawAlpha)
-    correctAlphaWhenFrameBufferSawNoAlpha(frameIndex);
 
   return true;
 }
 
 void GIFImageDecoder::clearFrameBuffer(size_t frameIndex) {
   if (m_reader &&
       m_frameBufferCache[frameIndex].getStatus() == ImageFrame::FramePartial) {
     // Reset the state of the partial frame in the reader so that the frame
     // can be decoded again when requested.
     m_reader->clearDecodeState(frameIndex);
@@ skipping 65 matching lines @@
   m_currentBufferSawAlpha = false;
 }
 
 bool GIFImageDecoder::canReusePreviousFrameBuffer(size_t frameIndex) const {
   DCHECK(frameIndex < m_frameBufferCache.size());
   return m_frameBufferCache[frameIndex].getDisposalMethod() !=
          ImageFrame::DisposeOverwritePrevious;
 }
 
 }  // namespace blink