Eliminate copies of encoded image data

third_party/WebKit/Source/platform/image-decoders/bmp/BMPImageReader.h

 /*
  * Copyright (c) 2008, 2009, Google 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 47 matching lines @@
         return *reinterpret_cast<const uint32_t*>(buffer);
     }
 
     // |parent| is the decoder that owns us.
     // |startOffset| points to the start of the BMP within the file.
     // |buffer| points at an empty ImageFrame that we'll initialize and
     // fill with decoded data.
     BMPImageReader(ImageDecoder* parent, size_t decodedAndHeaderOffset, size_t imgDataOffset, bool isInICO);
 
     void setBuffer(ImageFrame* buffer) { m_buffer = buffer; }
-    void setData(SharedBuffer* data)
+    void setData(SegmentReader* data)
     {
         m_data = data;
         m_fastReader.setData(data);
     }
 
     // Does the actual decoding.  If |onlySize| is true, decoding only
     // progresses as far as necessary to get the image size.  Returns
     // whether decoding succeeded.
     bool decodeBMP(bool onlySize);
 
@@ skipping 204 matching lines @@
     // depending on the value of |m_isTopDown|.
     void moveBufferToNextRow();
 
     // The decoder that owns us.
     ImageDecoder* m_parent;
 
     // The destination for the pixel data.
     ImageFrame* m_buffer;
 
     // The file to decode.
-    RefPtr<SharedBuffer> m_data;
+    RefPtr<SegmentReader> m_data;
     FastSharedBufferReader m_fastReader;
 
     // An index into |m_data| representing how much we've already decoded.
     size_t m_decodedOffset;
 
     // The file offset at which the BMP info header starts.
     size_t m_headerOffset;
 
     // The file offset at which the actual image bits start.  When decoding
     // ICO files, this is set to 0, since it's not stored anywhere in a
@@ skipping 58 matching lines @@
     // ICOs store a 1bpp "mask" immediately after the main bitmap image data
     // (and, confusingly, add its height to the biHeight value in the info
     // header, thus doubling it). If |m_isInICO| is true, this variable tracks
     // whether we've begun decoding this mask yet.
     bool m_decodingAndMask;
 };
 
 } // namespace blink
 
 #endif