Fix errors caused by unsafe conversions to/from size_t

third_party/WebKit/Source/platform/image-decoders/FastSharedBufferReader.h

 /*
  * Copyright (C) 2015 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 63 matching lines @@
     {
         return m_data->size();
     }
 
     // This class caches the last access for faster subsequent reads. This
     // method clears that cache in case the SharedBuffer has been modified
     // (i.e. with mergeSegmentsIntoBuffer).
     void clearCache();
 
 private:
-    void getSomeDataInternal(unsigned dataPosition) const;
+    void getSomeDataInternal(size_t dataPosition) const;
 
     RefPtr<SharedBuffer> m_data;
 
     // Caches the last segment of |m_data| accessed, since subsequent reads are
     // likely to re-access it.
     mutable const char* m_segment;
     mutable size_t m_segmentLength;
 
     // Data position in |m_data| pointed to by |m_segment|.
     mutable size_t m_dataPosition;
 };
 
 } // namespace blink
 
 #endif