Eliminate copies of encoded image data

third_party/WebKit/Source/platform/image-decoders/png/PNGImageDecoder.cpp

 /*
  * Copyright (C) 2006 Apple Computer, Inc.
  * Copyright (C) Research In Motion Limited 2009-2010. All rights reserved.
  *
  * Portions are Copyright (C) 2001 mozilla.org
  *
  * Other contributors:
  *   Stuart Parmenter <stuart@mozilla.com>
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 96 matching lines @@
     {
 #if USE(QCMSLIB)
         clearColorTransform();
 #endif
         png_destroy_read_struct(m_png ? &m_png : 0, m_info ? &m_info : 0, 0);
         ASSERT(!m_png && !m_info);
 
         m_readOffset = 0;
     }
 
-    bool decode(const SharedBuffer& data, bool sizeOnly)
+    bool decode(const SegmentReader& data, bool sizeOnly)
     {
         m_decodingSizeOnly = sizeOnly;
 
         // We need to do the setjmp here. Otherwise bad things will happen.
         if (setjmp(JMPBUF(m_png)))
             return m_decoder->setFailed();
 
         const char* segment;
         while (unsigned segmentLength = data.getSomeData(segment, m_readOffset)) {
             m_readOffset += segmentLength;
@@ skipping 375 matching lines @@
     // has failed.
     if (!m_reader->decode(*m_data, onlySize) && isAllDataReceived())
         setFailed();
 
     // If decoding is done or failed, we don't need the PNGImageReader anymore.
     if (isComplete(this) || failed())
         m_reader.clear();
 }
 
 } // namespace blink