Replace NULL with nullptr in webrtc/video.

webrtc/video/vie_channel.cc

 /*
  *  Copyright (c) 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 85 matching lines @@
       stats_observer_(new ChannelStatsObserver(this)),
       receive_stats_callback_(nullptr),
       incoming_video_stream_(nullptr),
       intra_frame_observer_(intra_frame_observer),
       rtt_stats_(rtt_stats),
       paced_sender_(paced_sender),
       packet_router_(packet_router),
       bandwidth_observer_(bandwidth_observer),
       transport_feedback_observer_(transport_feedback_observer),
       max_nack_reordering_threshold_(kMaxPacketAgeToNack),
-      pre_render_callback_(NULL),
+      pre_render_callback_(nullptr),
       last_rtt_ms_(0),
       rtp_rtcp_modules_(
           CreateRtpRtcpModules(!sender,
                                vie_receiver_.GetReceiveStatistics(),
                                transport,
                                intra_frame_observer_,
                                bandwidth_observer_.get(),
                                transport_feedback_observer_,
                                rtt_stats_,
                                &rtcp_packet_type_counter_observer_,
@@ skipping 191 matching lines @@
   return stats_observer_.get();
 }
 
 // Do not acquire the lock of |vcm_| in this function. Decode callback won't
 // necessarily be called from the decoding thread. The decoding thread may have
 // held the lock when calling VideoDecoder::Decode, Reset, or Release. Acquiring
 // the same lock in the path of decode callback can deadlock.
 int32_t ViEChannel::FrameToRender(VideoFrame& video_frame) {  // NOLINT
   rtc::CritScope lock(&crit_);
 
-  if (pre_render_callback_ != NULL)
+  if (pre_render_callback_)
     pre_render_callback_->FrameCallback(&video_frame);
 
   // TODO(pbos): Remove stream id argument.
   incoming_video_stream_->RenderFrame(0xFFFFFFFF, video_frame);
   return 0;
 }
 
 int32_t ViEChannel::ReceivedDecodedReferenceFrame(
   const uint64_t picture_id) {
   return rtp_rtcp_modules_[0]->SendRTCPReferencePictureSelection(picture_id);
@@ skipping 177 matching lines @@
   rtc::CritScope lock(&crit_);
   receive_stats_callback_ = receive_statistics_proxy;
 }
 
 void ViEChannel::SetIncomingVideoStream(
     IncomingVideoStream* incoming_video_stream) {
   rtc::CritScope lock(&crit_);
   incoming_video_stream_ = incoming_video_stream;
 }
 }  // namespace webrtc