replace NULL->nullptr in src/remoting.

remoting/host/local_input_monitor_unittest.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.
 
 #include "base/bind.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop/message_loop.h"
 #include "base/run_loop.h"
 #include "remoting/base/auto_thread_task_runner.h"
 #include "remoting/host/client_session_control.h"
@@ skipping 62 matching lines @@
       .Times(AnyNumber());
   EXPECT_CALL(client_session_control_, SetDisableInputs(_))
       .Times(0);
 
   {
     scoped_ptr<LocalInputMonitor> local_input_monitor =
         LocalInputMonitor::Create(task_runner_,
                                   task_runner_,
                                   task_runner_,
                                   client_session_control_factory_.GetWeakPtr());
-    task_runner_ = NULL;
+    task_runner_ = nullptr;
   }
 
   run_loop_.Run();
 }
 
 }  // namespace remoting