replace NULL->nullptr in src/remoting.

remoting/host/pairing_registry_delegate.h

 // Copyright 2013 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_PAIRING_REGISTRY_DELEGATE_H_
 #define REMOTING_HOST_PAIRING_REGISTRY_DELEGATE_H_
 
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "remoting/protocol/pairing_registry.h"
 
 namespace base {
 class SingleThreadTaskRunner;
 }  // namespace base
 
 namespace remoting {
 // Returns a platform-specific pairing registry delegate that will save to
-// permanent storage. Returns NULL on platforms that don't support pairing.
+// permanent storage. Returns nullptr on platforms that don't support pairing.
 scoped_ptr<protocol::PairingRegistry::Delegate>
 CreatePairingRegistryDelegate();
 
 // Convenience function which returns a new PairingRegistry, using the delegate
 // returned by CreatePairingRegistryDelegate(). The passed |task_runner| is used
 // to run the delegate's methods asynchronously.
 scoped_refptr<protocol::PairingRegistry> CreatePairingRegistry(
     scoped_refptr<base::SingleThreadTaskRunner> task_runner);
 
 }  // namespace remoting
 
 #endif  // REMOTING_HOST_PAIRING_REGISTRY_DELEGATE_H_