Replace NULL with nullptr or null in webrtc/base/.

webrtc/base/testclient.cc

 /*
  *  Copyright 2004 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 58 matching lines @@
     {
       CritScope cs(&crit_);
       if (packets_->size() != 0) {
         break;
       }
     }
     Thread::Current()->ProcessMessages(1);
   }
 
   // Return the first packet placed in the queue.
-  Packet* packet = NULL;
+  Packet* packet = nullptr;
   CritScope cs(&crit_);
   if (packets_->size() > 0) {
     packet = packets_->front();
     packets_->erase(packets_->begin());
   }
 
   return packet;
 }
 
 bool TestClient::CheckNextPacket(const char* buf, size_t size,
@@ skipping 20 matching lines @@
       res = false;
     }
   }
   prev_packet_timestamp_ = packet_timestamp;
   return res;
 }
 
 bool TestClient::CheckNoPacket() {
   bool res;
   Packet* packet = NextPacket(kNoPacketTimeoutMs);
-  res = (packet == NULL);
+  res = (packet == nullptr);
   delete packet;
   return res;
 }
 
 int TestClient::GetError() {
   return socket_->GetError();
 }
 
 int TestClient::SetOption(Socket::Option opt, int value) {
   return socket_->SetOption(opt, value);
@@ skipping 23 matching lines @@
     : addr(p.addr), buf(0), size(p.size), packet_time(p.packet_time) {
   buf = new char[size];
   memcpy(buf, p.buf, size);
 }
 
 TestClient::Packet::~Packet() {
   delete[] buf;
 }
 
 }  // namespace rtc