Replace NULL with nullptr in all C++ files.

webrtc/modules/desktop_capture/win/scoped_thread_desktop.cc

 /*
  *  Copyright (c) 2013 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/modules/desktop_capture/win/scoped_thread_desktop.h"
 
 #include "webrtc/system_wrappers/include/logging.h"
 
 #include "webrtc/modules/desktop_capture/win/desktop.h"
 
 namespace webrtc {
 
 ScopedThreadDesktop::ScopedThreadDesktop()
     : initial_(Desktop::GetThreadDesktop()) {
 }
 
 ScopedThreadDesktop::~ScopedThreadDesktop() {
   Revert();
 }
 
 bool ScopedThreadDesktop::IsSame(const Desktop& desktop) {
-  if (assigned_.get() != NULL) {
+  if (assigned_.get() != nullptr) {
     return assigned_->IsSame(desktop);
   } else {
     return initial_->IsSame(desktop);
   }
 }
 
 void ScopedThreadDesktop::Revert() {
-  if (assigned_.get() != NULL) {
+  if (assigned_.get() != nullptr) {
     initial_->SetThreadDesktop();
     assigned_.reset();
   }
 }
 
 bool ScopedThreadDesktop::SetThreadDesktop(Desktop* desktop) {
   Revert();
 
   std::unique_ptr<Desktop> scoped_desktop(desktop);
 
   if (initial_->IsSame(*desktop))
     return true;
 
   if (!desktop->SetThreadDesktop())
     return false;
 
   assigned_.reset(scoped_desktop.release());
   return true;
 }
 
 }  // namespace webrtc