Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/modules/mediastream/UserMediaRequest.cpp

 /*
  * Copyright (C) 2011 Ericsson AB. All rights reserved.
  * Copyright (C) 2012 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.
@@ skipping 49 matching lines @@
             constraints = MediaConstraintsImpl::create();
     }
 
     return constraints;
 }
 
 PassRefPtr<UserMediaRequest> UserMediaRequest::create(ExecutionContext* context, UserMediaController* controller, const Dictionary& options, PassOwnPtr<NavigatorUserMediaSuccessCallback> successCallback, PassOwnPtr<NavigatorUserMediaErrorCallback> errorCallback, ExceptionState& exceptionState)
 {
     blink::WebMediaConstraints audio = parseOptions(options, "audio", exceptionState);
     if (exceptionState.hadException())
-        return 0;
+        return nullptr;
 
     blink::WebMediaConstraints video = parseOptions(options, "video", exceptionState);
     if (exceptionState.hadException())
-        return 0;
+        return nullptr;
 
     if (audio.isNull() && video.isNull())
-        return 0;
+        return nullptr;
 
     return adoptRef(new UserMediaRequest(context, controller, audio, video, successCallback, errorCallback));
 }
 
 UserMediaRequest::UserMediaRequest(ExecutionContext* context, UserMediaController* controller, blink::WebMediaConstraints audio, blink::WebMediaConstraints video, PassOwnPtr<NavigatorUserMediaSuccessCallback> successCallback, PassOwnPtr<NavigatorUserMediaErrorCallback> errorCallback)
     : ContextLifecycleObserver(context)
     , m_audio(audio)
     , m_video(video)
     , m_controller(controller)
     , m_successCallback(successCallback)
@@ skipping 89 matching lines @@
 
     if (m_controller) {
         m_controller->cancelUserMediaRequest(this);
         m_controller = 0;
     }
 
     ContextLifecycleObserver::contextDestroyed();
 }
 
 } // namespace WebCore