Replace NULL with nullptr in all C++ files.

webrtc/modules/remote_bitrate_estimator/test/estimators/remb.cc

 /*
  *  Copyright (c) 2015 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 90 matching lines @@
   clock_.AdvanceTimeMilliseconds(arrival_time_ms - clock_.TimeInMilliseconds());
   ASSERT_TRUE(arrival_time_ms == clock_.TimeInMilliseconds());
 
   // Log received packet information.
   BweReceiver::ReceivePacket(arrival_time_ms, media_packet);
 }
 
 FeedbackPacket* RembReceiver::GetFeedback(int64_t now_ms) {
   BWE_TEST_LOGGING_CONTEXT("Remb");
   uint32_t estimated_bps = 0;
-  RembFeedback* feedback = NULL;
+  RembFeedback* feedback = nullptr;
   if (LatestEstimate(&estimated_bps)) {
     StatisticianMap statisticians = recv_stats_->GetActiveStatisticians();
     RTCPReportBlock report_block;
     if (!statisticians.empty()) {
       latest_report_block_ = BuildReportBlock(statisticians.begin()->second);
     }
 
     feedback = new RembFeedback(flow_id_, now_ms * 1000, last_feedback_ms_,
                                 estimated_bps, latest_report_block_);
     last_feedback_ms_ = now_ms;
@@ skipping 32 matching lines @@
     }
     latest_estimate_bps_ = bps;
   }
   *estimate_bps = latest_estimate_bps_;
   return true;
 }
 
 }  // namespace bwe
 }  // namespace testing
 }  // namespace webrtc