replace NULL->nullptr in src/remoting.

remoting/host/posix/signal_handler.cc

 // 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.
 
 // TODO(jamiewalch): Add unit tests for this.
 
 #include "remoting/host/posix/signal_handler.h"
 
 #include <errno.h>
 #include <signal.h>
@@ skipping 44 matching lines @@
     for (SignalHandlers::const_iterator i = signal_handlers_.begin();
          i != signal_handlers_.end();
          ++i) {
       if (i->first == buffer) {
         i->second.Run(i->first);
       }
     }
   }
 }
 
-SignalListener* g_signal_listener = NULL;
+SignalListener* g_signal_listener = nullptr;
 int g_write_fd = 0;
 
 void GlobalSignalHandler(int signal) {
   char byte = signal;
   ignore_result(write(g_write_fd, &byte, 1));
 }
 
 }  // namespace
 
 // RegisterSignalHandler registers a signal handler that writes a byte to a
@@ skipping 32 matching lines @@
   }
   if (signal(signal_number, GlobalSignalHandler) == SIG_ERR) {
     LOG(ERROR) << "signal() failed: " << errno;
     return false;
   }
   g_signal_listener->AddSignalHandler(signal_number, handler);
   return true;
 }
 
 }  // namespace remoting