Remove image decoder down sampling

Source/core/platform/image-decoders/png/PNGImageDecoder.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 24 matching lines @@
 
     // This class decodes the PNG image format.
     class PNGImageDecoder : public ImageDecoder {
     public:
         PNGImageDecoder(ImageSource::AlphaOption, ImageSource::GammaAndColorProfileOption);
         virtual ~PNGImageDecoder();
 
         // ImageDecoder
         virtual String filenameExtension() const { return "png"; }
         virtual bool isSizeAvailable();
-        virtual bool setSize(unsigned width, unsigned height);
         virtual ImageFrame* frameBufferAtIndex(size_t index);
         // CAUTION: setFailed() deletes |m_reader|.  Be careful to avoid
         // accessing deleted memory, especially when calling this from inside
         // PNGImageReader!
         virtual bool setFailed();
 
         // Callbacks from libpng
         void headerAvailable();
         void rowAvailable(unsigned char* rowBuffer, unsigned rowIndex, int interlacePass);
         void pngComplete();
 
         bool isComplete() const
         {
             return !m_frameBufferCache.isEmpty() && (m_frameBufferCache.first().status() == ImageFrame::FrameComplete);
         }
 
     private:
         // Decodes the image.  If |onlySize| is true, stops decoding after
         // calculating the image size.  If decoding fails but there is no more
         // data coming, sets the "decode failure" flag.
         void decode(bool onlySize);
 
         OwnPtr<PNGImageReader> m_reader;
         bool m_doNothingOnFailure;
     };
 
 } // namespace WebCore
 
 #endif