Remove opaque alpha channel special case

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 63 matching lines @@
   void ClearFrameBuffer(size_t frame_index) override;
   virtual void DecodeSize() { Parse(kGIFSizeQuery); }
   size_t DecodeFrameCount() override;
   void InitializeNewFrame(size_t) override;
   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);
 
-  // Reset the alpha tracker for this frame. Before calling this method, the
-  // caller must verify that the frame exists.
-  void OnInitFrameBuffer(size_t) override;
-
   // When the disposal method of the frame is DisposeOverWritePrevious, the
   // next frame will use the previous frame's buffer as its starting state, so
   // we can't take over the data in that case. Before calling this method, the
   // caller must verify that the frame exists.
   bool CanReusePreviousFrameBuffer(size_t) const override;
 
-  bool current_buffer_saw_alpha_;
   mutable int repetition_count_;
   std::unique_ptr<GIFImageReader> reader_;
 };
 
 }  // namespace blink
 
 #endif