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

webrtc/base/platform_thread.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 131 matching lines @@
 
 void PlatformThread::Start() {
   RTC_DCHECK(thread_checker_.CalledOnValidThread());
   RTC_DCHECK(!thread_) << "Thread already started?";
 #if defined(WEBRTC_WIN)
   stop_ = false;
 
   // See bug 2902 for background on STACK_SIZE_PARAM_IS_A_RESERVATION.
   // Set the reserved stack stack size to 1M, which is the default on Windows
   // and Linux.
-  thread_ = ::CreateThread(NULL, 1024 * 1024, &StartThread, this,
+  thread_ = ::CreateThread(nullptr, 1024 * 1024, &StartThread, this,
                            STACK_SIZE_PARAM_IS_A_RESERVATION, &thread_id_);
   RTC_CHECK(thread_) << "CreateThread failed";
   RTC_DCHECK(thread_id_);
 #else
   ThreadAttributes attr;
   // Set the stack stack size to 1M.
   pthread_attr_setstacksize(&attr, 1024 * 1024);
   RTC_CHECK_EQ(0, pthread_create(&thread_, &attr, &StartThread, this));
 #endif  // defined(WEBRTC_WIN)
 }
@@ skipping 149 matching lines @@
 #if defined(WEBRTC_WIN)
 bool PlatformThread::QueueAPC(PAPCFUNC function, ULONG_PTR data) {
   RTC_DCHECK(thread_checker_.CalledOnValidThread());
   RTC_DCHECK(IsRunning());
 
   return QueueUserAPC(function, thread_, data) != FALSE;
 }
 #endif
 
 }  // namespace rtc