replace NULL->nullptr in src/remoting.

remoting/protocol/datagram_channel_factory.h

 // Copyright 2014 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_PROTOCOL_DATAGRAM_CHANNEL_FACTORY_H_
 #define REMOTING_PROTOCOL_DATAGRAM_CHANNEL_FACTORY_H_
 
 #include <string>
 
 #include "base/callback_forward.h"
 
 namespace net {
 class Socket;
 }  // namespace net
 
 namespace remoting {
 namespace protocol {
 
 class DatagramChannelFactory {
  public:
   typedef base::Callback<void(scoped_ptr<net::Socket>)>
       ChannelCreatedCallback;
 
   DatagramChannelFactory() {}
 
   // Creates new channels and calls the |callback| when then new channel is
-  // created and connected. The |callback| is called with NULL if channel setup
-  // failed for any reason. Callback may be called synchronously, before the
-  // call returns. All channels must be destroyed, and CancelChannelCreation()
-  // called for any pending channels, before the factory is destroyed.
+  // created and connected. The |callback| is called with nullptr if channel
+  // setup failed for any reason. Callback may be called synchronously, before
+  // the call returns. All channels must be destroyed, and
+  // CancelChannelCreation() called for any pending channels, before the factory
+  // is destroyed.
   virtual void CreateChannel(const std::string& name,
                              const ChannelCreatedCallback& callback) = 0;
 
   // Cancels a pending CreateChannel() operation for the named channel. If the
   // channel creation already completed then canceling it has no effect. When
   // shutting down this method must be called for each channel pending creation.
   virtual void CancelChannelCreation(const std::string& name) = 0;
 
  protected:
   virtual ~DatagramChannelFactory() {}
 
  private:
   DISALLOW_COPY_AND_ASSIGN(DatagramChannelFactory);
 };
 
 }  // namespace protocol
 }  // namespace remoting
 
 #endif  // REMOTING_PROTOCOL_DATAGRAM_CHANNEL_FACTORY_H_