replace NULL->nullptr in src/remoting.

remoting/host/sas_injector.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef REMOTING_HOST_SAS_INJECTOR_H_
 #define REMOTING_HOST_SAS_INJECTOR_H_
 
 #include "base/memory/scoped_ptr.h"
 
 namespace remoting {
 
 // Provides a way to simulate a Secure Attention Sequence (SAS). The default
 // sequence is Ctrl+Alt+Delete.
 class SasInjector {
  public:
   virtual ~SasInjector() {}
 
   // Sends Secure Attention Sequence to the console session.
   virtual bool InjectSas() = 0;
 
   // Creates an instance of SasInjector if supported by the OS, otherwise
-  // returns NULL.
+  // returns nullptr.
   static scoped_ptr<SasInjector> Create();
 };
 
 }  // namespace remoting
 
 #endif  // REMOTING_HOST_SAS_INJECTOR_H_