Replace NULL with nullptr in all C++ files.

webrtc/pc/peerconnectionfactory.cc

 /*
  *  Copyright 2004 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 155 matching lines @@
       default_adm_(default_adm),
       // TODO(ossu): Take care of audio_encoder_factory (see bug 5806).
       audio_decoder_factory_(audio_decoder_factory),
       video_encoder_factory_(video_encoder_factory),
       video_decoder_factory_(video_decoder_factory),
       external_audio_mixer_(audio_mixer) {
   RTC_DCHECK(network_thread);
   RTC_DCHECK(worker_thread);
   RTC_DCHECK(signaling_thread);
   // TODO: Currently there is no way creating an external adm in
-  // libjingle source tree. So we can 't currently assert if this is NULL.
-  // RTC_DCHECK(default_adm != NULL);
+  // libjingle source tree. So we can 't currently assert if this is null.
+  // RTC_DCHECK(default_adm != null);
 }
 
 PeerConnectionFactory::~PeerConnectionFactory() {
   RTC_DCHECK(signaling_thread_->IsCurrent());
   channel_manager_.reset(nullptr);
 
   // Make sure |worker_thread_| and |signaling_thread_| outlive
   // |default_socket_factory_| and |default_network_manager_|.
   default_socket_factory_ = nullptr;
   default_network_manager_ = nullptr;
@@ skipping 202 matching lines @@
 }
 
 cricket::MediaEngineInterface* PeerConnectionFactory::CreateMediaEngine_w() {
   RTC_DCHECK(worker_thread_ == rtc::Thread::Current());
   return cricket::WebRtcMediaEngineFactory::Create(
       default_adm_.get(), audio_decoder_factory_, video_encoder_factory_.get(),
       video_decoder_factory_.get(), external_audio_mixer_);
 }
 
 }  // namespace webrtc