Replace NULL with nullptr in all C++ files.

webrtc/voice_engine/test/channel_transport/udp_socket_posix.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 20 matching lines @@
     : _id(id),
       _closeBlockingCompletedCond(true, false),
       _readyForDeletionCond(true, false)
 {
     WEBRTC_TRACE(kTraceMemory, kTraceTransport, id,
                  "UdpSocketPosix::UdpSocketPosix()");
 
     _wantsIncoming = false;
     _mgr = mgr;
 
-    _obj = NULL;
-    _incomingCb = NULL;
+    _obj = nullptr;
+    _incomingCb = nullptr;
     _readyForDeletion = false;
     _closeBlockingActive = false;
     _closeBlockingCompleted = false;
     if(ipV6Enable)
     {
         _socket = socket(AF_INET6, SOCK_DGRAM, IPPROTO_UDP);
     }
     else {
         _socket = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
     }
@@ skipping 209 matching lines @@
     WEBRTC_TRACE(kTraceDebug, kTraceTransport, _id,
                  "calling UdpSocketManager::RemoveSocket()...");
     _mgr->RemoveSocket(this);
     // After this, the socket should may be or will be as deleted. Return
     // immediately.
     return true;
 }
 
 }  // namespace test
 }  // namespace webrtc