Replace NULL with nullptr in all C++ files.

webrtc/voice_engine/monitor_module.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.
  */
 
 #include "webrtc/base/timeutils.h"
 #include "webrtc/voice_engine/monitor_module.h"
 
 namespace webrtc  {
 
 namespace voe  {
 
-MonitorModule::MonitorModule() :
-    _observerPtr(NULL),
-    _lastProcessTime(rtc::TimeMillis())
-{
-}
+MonitorModule::MonitorModule()
+    : _observerPtr(nullptr), _lastProcessTime(rtc::TimeMillis()) {}
 
 MonitorModule::~MonitorModule()
 {
 }
 
 int32_t
 MonitorModule::RegisterObserver(MonitorObserver& observer)
 {
     rtc::CritScope lock(&_callbackCritSect);
     if (_observerPtr)
     {
         return -1;
     }
     _observerPtr = &observer;
     return 0;
 }
 
 int32_t
 MonitorModule::DeRegisterObserver()
 {
     rtc::CritScope lock(&_callbackCritSect);
     if (!_observerPtr)
     {
         return 0;
     }
-    _observerPtr = NULL;
+    _observerPtr = nullptr;
     return 0;
 }
 
 int64_t
 MonitorModule::TimeUntilNextProcess()
 {
     int64_t now = rtc::TimeMillis();
     const int64_t kAverageProcessUpdateTimeMs = 1000;
     return kAverageProcessUpdateTimeMs - (now - _lastProcessTime);
 }
 
 void
 MonitorModule::Process()
 {
     _lastProcessTime = rtc::TimeMillis();
     rtc::CritScope lock(&_callbackCritSect);
     if (_observerPtr)
     {
         _observerPtr->OnPeriodicProcess();
     }
 }
 
 }  // namespace voe
 
 }  // namespace webrtc