replace NULL->nullptr in src/remoting.

remoting/signaling/fake_signal_strategy.cc

 // 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.
 
 #include "remoting/signaling/fake_signal_strategy.h"
 
 #include "base/bind.h"
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/single_thread_task_runner.h"
@@ skipping 118 matching lines @@
   const std::string& to_field = stanza_ptr->Attr(buzz::QN_TO);
   if (to_field != jid_) {
     LOG(WARNING) << "Dropping stanza that is addressed to " << to_field
                  << ". Local jid: " << jid_
                  << ". Message content: " << stanza_ptr->Str();
     return;
   }
 
   ObserverListBase<Listener>::Iterator it(listeners_);
   Listener* listener;
-  while ((listener = it.GetNext()) != NULL) {
+  while ((listener = it.GetNext()) != nullptr) {
     if (listener->OnSignalStrategyIncomingStanza(stanza_ptr))
       break;
   }
 }
 
 void FakeSignalStrategy::SetPeerCallback(const PeerCallback& peer_callback) {
   peer_callback_ = peer_callback;
 }
 
 }  // namespace remoting