remoting/host: Fix cpplint warning of header guards.

remoting/host/wts_console_observer_win.h

 // 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.
 
-#ifndef REMOTING_HOST_wts_console_observer_win_H_
-#define REMOTING_HOST_wts_console_observer_win_H_
+#ifndef REMOTING_HOST_WTS_CONSOLE_OBSERVER_WIN_H_
+#define REMOTING_HOST_WTS_CONSOLE_OBSERVER_WIN_H_
+#pragma once
 
 #include <windows.h>
 
 #include "base/basictypes.h"
 
 namespace remoting {
 
 // Provides callbacks for monitoring events on a WTS terminal.
 class WtsConsoleObserver {
  public:
   virtual ~WtsConsoleObserver() {}
 
   // Called when |session_id| attaches to the console.
   virtual void OnSessionAttached(uint32 session_id) = 0;
 
   // Called when a session detaches from the console.
   virtual void OnSessionDetached() = 0;
 
  protected:
   WtsConsoleObserver() {}
 
  private:
   DISALLOW_COPY_AND_ASSIGN(WtsConsoleObserver);
 };
 
 }  // namespace remoting
 
-#endif  // REMOTING_HOST_wts_console_observer_win_H_
+#endif  // REMOTING_HOST_WTS_CONSOLE_OBSERVER_WIN_H_