Replace NULL with nullptr in all C++ files.

webrtc/pc/remoteaudiosource.cc

 /*
  *  Copyright 2014 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 84 matching lines @@
   return true;
 }
 
 void RemoteAudioSource::SetVolume(double volume) {
   RTC_DCHECK(volume >= 0 && volume <= 10);
   for (auto* observer : audio_observers_)
     observer->OnSetVolume(volume);
 }
 
 void RemoteAudioSource::RegisterAudioObserver(AudioObserver* observer) {
-  RTC_DCHECK(observer != NULL);
+  RTC_DCHECK(observer != nullptr);
   RTC_DCHECK(std::find(audio_observers_.begin(), audio_observers_.end(),
                        observer) == audio_observers_.end());
   audio_observers_.push_back(observer);
 }
 
 void RemoteAudioSource::UnregisterAudioObserver(AudioObserver* observer) {
-  RTC_DCHECK(observer != NULL);
+  RTC_DCHECK(observer != nullptr);
   audio_observers_.remove(observer);
 }
 
 void RemoteAudioSource::AddSink(AudioTrackSinkInterface* sink) {
   RTC_DCHECK(main_thread_->IsCurrent());
   RTC_DCHECK(sink);
 
   if (state_ != MediaSourceInterface::kLive) {
     LOG(LS_ERROR) << "Can't register sink as the source isn't live.";
     return;
@@ skipping 28 matching lines @@
 }
 
 void RemoteAudioSource::OnMessage(rtc::Message* msg) {
   RTC_DCHECK(main_thread_->IsCurrent());
   sinks_.clear();
   state_ = MediaSourceInterface::kEnded;
   FireOnChanged();
 }
 
 }  // namespace webrtc