Use downloadToFile option when XHR downloads a Blob

Source/core/xml/XMLHttpRequest.h

 /*
  *  Copyright (C) 2003, 2006, 2008 Apple Inc. All rights reserved.
  *  Copyright (C) 2005, 2006 Alexey Proskuryakov <ap@nypop.com>
  *  Copyright (C) 2011 Google Inc. All rights reserved.
  *  Copyright (C) 2012 Intel Corporation
  *
  *  This library is free software; you can redistribute it and/or
  *  modify it under the terms of the GNU Lesser General Public
  *  License as published by the Free Software Foundation; either
  *  version 2 of the License, or (at your option) any later version.
@@ skipping 140 matching lines @@
 
     virtual void refEventTarget() OVERRIDE { ref(); }
     virtual void derefEventTarget() OVERRIDE { deref(); }
 
     Document* document() const;
     SecurityOrigin* securityOrigin() const;
 
     virtual void didSendData(unsigned long long bytesSent, unsigned long long totalBytesToBeSent);
     virtual void didReceiveResponse(unsigned long identifier, const ResourceResponse&);
     virtual void didReceiveData(const char* data, int dataLength);
+    // When "blob" is specified as the responseType attribute, didDownloadData
+    // is called instead of didReceiveData.
+    virtual void didDownloadData(int dataLength);
     virtual void didFinishLoading(unsigned long identifier, double finishTime);
     virtual void didFail(const ResourceError&);
     virtual void didFailRedirectCheck();
 
     String responseMIMEType() const;
     bool responseIsXML() const;
 
     bool areMethodAndURLValidForSend();
 
     bool initSend(ExceptionState&);
     void sendBytesData(const void*, size_t, ExceptionState&);
 
     String getRequestHeader(const AtomicString& name) const;
     void setRequestHeaderInternal(const AtomicString& name, const String& value);
 
+    void trackProgress(int dataLength);
     void changeState(State newState);
     void callReadyStateChangeListener();
     void dropProtectionSoon();
     void dropProtection(Timer<XMLHttpRequest>* = 0);
     void internalAbort(DropProtection = DropProtectionSync);
     void clearResponse();
     void clearResponseBuffers();
     void clearRequest();
 
     void createRequest(ExceptionState&);
@@ skipping 49 matching lines @@
 
     // An enum corresponding to the allowed string values for the responseType attribute.
     ResponseTypeCode m_responseTypeCode;
     Timer<XMLHttpRequest> m_protectionTimer;
     RefPtr<SecurityOrigin> m_securityOrigin;
 };
 
 } // namespace WebCore
 
 #endif // XMLHttpRequest_h