Correct data size argument type in resource loading path to unsigned

Source/core/loader/TextTrackLoader.h

 /*
  * Copyright (C) 2011 Apple 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 52 matching lines @@
     enum State { Idle, Loading, Finished, Failed };
     State loadState() { return m_state; }
 
     void getNewCues(WillBeHeapVector<RefPtrWillBeMember<VTTCue> >& outputCues);
     void getNewRegions(WillBeHeapVector<RefPtrWillBeMember<VTTRegion> >& outputRegions);
 
     void trace(Visitor*);
 
 private:
     // RawResourceClient
-    virtual void dataReceived(Resource*, const char* data, int length) OVERRIDE;
+    virtual void dataReceived(Resource*, const char* data, unsigned length) OVERRIDE;
     virtual void notifyFinished(Resource*) OVERRIDE;
 
     // VTTParserClient
     virtual void newCuesParsed() OVERRIDE;
     virtual void newRegionsParsed() OVERRIDE;
     virtual void fileFailedToParse() OVERRIDE;
 
     TextTrackLoader(TextTrackLoaderClient&, Document&);
 
     void cueLoadTimerFired(Timer<TextTrackLoader>*);
     void corsPolicyPreventedLoad(SecurityOrigin*, const KURL&);
 
     Document& document() const { return *m_document; }
 
     TextTrackLoaderClient& m_client;
     OwnPtrWillBeMember<VTTParser> m_cueParser;
     // FIXME: Remove this pointer and get the Document from m_client.
     RawPtrWillBeMember<Document> m_document;
     Timer<TextTrackLoader> m_cueLoadTimer;
     State m_state;
     bool m_newCuesAvailable;
 };
 
 } // namespace blink
 
 #endif