Replace NULL with nullptr in all C++ files.

webrtc/modules/remote_bitrate_estimator/test/estimators/nada.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 81 matching lines @@
   }
 
   // Log received packet information.
   BweReceiver::ReceivePacket(arrival_time_ms, media_packet);
 }
 
 FeedbackPacket* NadaBweReceiver::GetFeedback(int64_t now_ms) {
   const int64_t kPacketLossPenaltyMs = 1000;  // Referred as d_L.
 
   if (now_ms - last_feedback_ms_ < 100) {
-    return NULL;
+    return nullptr;
   }
 
   float loss_fraction = RecentPacketLossRatio();
 
   int64_t loss_signal_ms =
       static_cast<int64_t>(loss_fraction * kPacketLossPenaltyMs + 0.5f);
   int64_t congestion_signal_ms = est_queuing_delay_signal_ms_ + loss_signal_ms;
 
   float derivative = 0.0f;
   if (last_feedback_ms_ > 0) {
@@ skipping 171 matching lines @@
        (kTheta - (bitrate_kbps_ - kMinNadaBitrateKbps) * x_hat)) /
           (kTauOMs * kTauOMs) +
       0.5f);
 
   bitrate_kbps_ = bitrate_kbps_ + smoothing_factor * original_increase;
 }
 
 }  // namespace bwe
 }  // namespace testing
 }  // namespace webrtc