Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/modules/mediastream/RTCDTMFSender.cpp

 /*
  * Copyright (C) 2013 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:
  * 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 32 matching lines @@
 static const long maxToneDurationMs = 6000;
 static const long minInterToneGapMs = 50;
 static const long defaultInterToneGapMs = 50;
 
 PassRefPtr<RTCDTMFSender> RTCDTMFSender::create(ExecutionContext* context, blink::WebRTCPeerConnectionHandler* peerConnectionHandler, PassRefPtr<MediaStreamTrack> prpTrack, ExceptionState& exceptionState)
 {
     RefPtr<MediaStreamTrack> track = prpTrack;
     OwnPtr<blink::WebRTCDTMFSenderHandler> handler = adoptPtr(peerConnectionHandler->createDTMFSender(track->component()));
     if (!handler) {
         exceptionState.throwDOMException(NotSupportedError, "The MediaStreamTrack provided is not an element of a MediaStream that's currently in the local streams set.");
-        return 0;
+        return nullptr;
     }
 
     RefPtr<RTCDTMFSender> dtmfSender = adoptRef(new RTCDTMFSender(context, track, handler.release()));
     dtmfSender->suspendIfNeeded();
     return dtmfSender.release();
 }
 
 RTCDTMFSender::RTCDTMFSender(ExecutionContext* context, PassRefPtr<MediaStreamTrack> track, PassOwnPtr<blink::WebRTCDTMFSenderHandler> handler)
     : ActiveDOMObject(context)
     , m_track(track)
@@ skipping 96 matching lines @@
 
     Vector<RefPtr<Event> > events;
     events.swap(m_scheduledEvents);
 
     Vector<RefPtr<Event> >::iterator it = events.begin();
     for (; it != events.end(); ++it)
         dispatchEvent((*it).release());
 }
 
 } // namespace WebCore