Revert of Do not consolidate data in BMPImageDecoder

Source/platform/image-decoders/bmp/BMPImageDecoder.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 36 matching lines @@
     // CAUTION: setFailed() deletes |m_reader|.  Be careful to avoid
     // accessing deleted memory, especially when calling this from inside
     // BMPImageReader!
     bool setFailed() override;
 
 private:
     // ImageDecoder:
     void decodeSize() override { decode(true); }
     void decode(size_t) override { decode(false); }
 
+    inline uint32_t readUint32(int offset) const
+    {
+        return BMPImageReader::readUint32(m_data.get(), m_decodedOffset + offset);
+    }
+
     // 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);
 
     // Decodes the image.  If |onlySize| is true, stops decoding after
     // calculating the image size. Returns whether decoding succeeded.
     bool decodeHelper(bool onlySize);
 
     // Processes the file header at the beginning of the data.  Sets
     // |imgDataOffset| based on the header contents. Returns true if the
     // file header could be decoded.
     bool processFileHeader(size_t& imgDataOffset);
 
     // An index into |m_data| representing how much we've already decoded.
     // Note that this only tracks data _this_ class decodes; once the
     // BMPImageReader takes over this will not be updated further.
     size_t m_decodedOffset;
 
     // The reader used to do most of the BMP decoding.
     OwnPtr<BMPImageReader> m_reader;
 };
 
 } // namespace blink
 
 #endif