replace NULL->nullptr in src/remoting.

remoting/host/curtain_mode_linux.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 "remoting/host/curtain_mode.h"
 
 #include <X11/extensions/XInput.h>
 
 #include "base/callback.h"
 #include "base/single_thread_task_runner.h"
@@ skipping 29 matching lines @@
                   "X server";
   }
 
   return activated;
 }
 
 bool CurtainModeLinux::IsXvfbSession() {
   // Try to identify an Xvfb session. There's no way to query what X server we
   // are running under, so we check for the Xvfb input devices.
   // TODO(rmsousa): Find a similar way to determine that the *output* is secure.
-  Display* display = XOpenDisplay(NULL);
+  Display* display = XOpenDisplay(nullptr);
   int opcode, event, error;
   if (!XQueryExtension(display, "XInputExtension", &opcode, &event, &error)) {
     // If XInput is not available, assume it is not an Xvfb session.
     LOG(ERROR) << "X Input extension not available: " << error;
     XCloseDisplay(display);
     return false;
   }
   int num_devices;
   XDeviceInfo* devices;
   bool found_xvfb_mouse = false;
@@ skipping 39 matching lines @@
 
 // static
 scoped_ptr<CurtainMode> CurtainMode::Create(
     scoped_refptr<base::SingleThreadTaskRunner> caller_task_runner,
     scoped_refptr<base::SingleThreadTaskRunner> ui_task_runner,
     base::WeakPtr<ClientSessionControl> client_session_control) {
   return make_scoped_ptr(new CurtainModeLinux());
 }
 
 }  // namespace remoting