Replace NULL with nullptr in webrtc/video.

webrtc/video/receive_statistics_proxy.cc

 /*
  *  Copyright (c) 2013 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 254 matching lines @@
 }
 
 void ReceiveStatisticsProxy::OnDiscardedPacketsUpdated(int discarded_packets) {
   rtc::CritScope lock(&crit_);
   stats_.discarded_packets = discarded_packets;
 }
 
 void ReceiveStatisticsProxy::OnPreDecode(
     const EncodedImage& encoded_image,
     const CodecSpecificInfo* codec_specific_info) {
-  if (codec_specific_info == nullptr || encoded_image.qp_ == -1) {
+  if (!codec_specific_info || encoded_image.qp_ == -1) {
     return;
   }
   if (codec_specific_info->codecType == kVideoCodecVP8) {
     qp_counters_.vp8.Add(encoded_image.qp_);
   }
 }
 
 void ReceiveStatisticsProxy::SampleCounter::Add(int sample) {
   sum += sample;
   ++num_samples;
 }
 
 int ReceiveStatisticsProxy::SampleCounter::Avg(int min_required_samples) const {
   if (num_samples < min_required_samples || num_samples == 0)
     return -1;
   return sum / num_samples;
 }
 
 }  // namespace webrtc