Replace NULL with nullptr in all C++ files.

webrtc/pc/mediastream.cc

 /*
  *  Copyright 2011 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 39 matching lines @@
 }
 
 bool MediaStream::RemoveTrack(VideoTrackInterface* track) {
   return RemoveTrack<VideoTrackVector>(&video_tracks_, track);
 }
 
 rtc::scoped_refptr<AudioTrackInterface>
 MediaStream::FindAudioTrack(const std::string& track_id) {
   AudioTrackVector::iterator it = FindTrack(&audio_tracks_, track_id);
   if (it == audio_tracks_.end())
-    return NULL;
+    return nullptr;
   return *it;
 }
 
 rtc::scoped_refptr<VideoTrackInterface>
 MediaStream::FindVideoTrack(const std::string& track_id) {
   VideoTrackVector::iterator it = FindTrack(&video_tracks_, track_id);
   if (it == video_tracks_.end())
-    return NULL;
+    return nullptr;
   return *it;
 }
 
 template <typename TrackVector, typename Track>
 bool MediaStream::AddTrack(TrackVector* tracks, Track* track) {
   typename TrackVector::iterator it = FindTrack(tracks, track->id());
   if (it != tracks->end())
     return false;
   tracks->push_back(track);
   FireOnChanged();
   return true;
 }
 
 template <typename TrackVector>
 bool MediaStream::RemoveTrack(TrackVector* tracks,
                               MediaStreamTrackInterface* track) {
-  RTC_DCHECK(tracks != NULL);
+  RTC_DCHECK(tracks != nullptr);
   if (!track)
     return false;
   typename TrackVector::iterator it = FindTrack(tracks, track->id());
   if (it == tracks->end())
     return false;
   tracks->erase(it);
   FireOnChanged();
   return true;
 }
 
 }  // namespace webrtc