Fix compilation issues of std::unique_ptr

webrtc/pc/videocapturertracksource.cc

 /*
  *  Copyright 2012 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 244 matching lines @@
 }  // anonymous namespace
 
 namespace webrtc {
 
 rtc::scoped_refptr<VideoTrackSourceInterface> VideoCapturerTrackSource::Create(
     rtc::Thread* worker_thread,
     std::unique_ptr<cricket::VideoCapturer> capturer,
     const webrtc::MediaConstraintsInterface* constraints,
     bool remote) {
   RTC_DCHECK(worker_thread != NULL);
-  RTC_DCHECK(capturer != NULL);
+  RTC_DCHECK(capturer != nullptr);
   rtc::scoped_refptr<VideoCapturerTrackSource> source(
       new rtc::RefCountedObject<VideoCapturerTrackSource>(
           worker_thread, std::move(capturer), remote));
   source->Initialize(constraints);
   return source;
 }
 
 rtc::scoped_refptr<VideoTrackSourceInterface> VideoCapturerTrackSource::Create(
     rtc::Thread* worker_thread,
     std::unique_ptr<cricket::VideoCapturer> capturer,
     bool remote) {
   RTC_DCHECK(worker_thread != NULL);
-  RTC_DCHECK(capturer != NULL);
+  RTC_DCHECK(capturer != nullptr);
   rtc::scoped_refptr<VideoCapturerTrackSource> source(
       new rtc::RefCountedObject<VideoCapturerTrackSource>(
           worker_thread, std::move(capturer), remote));
   source->Initialize(nullptr);
   return source;
 }
 
 VideoCapturerTrackSource::VideoCapturerTrackSource(
     rtc::Thread* worker_thread,
     std::unique_ptr<cricket::VideoCapturer> capturer,
@@ skipping 103 matching lines @@
                   rtc::Unretained(this), capturer, capture_state));
     return;
   }
 
   if (capturer == video_capturer_.get()) {
     SetState(GetReadyState(capture_state));
   }
 }
 
 }  // namespace webrtc