chromeos: Move files in //ash/common to //ash, part 1

ash/system/screen_security/screen_share_observer.h

 // Copyright 2013 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 ASH_COMMON_SYSTEM_CHROMEOS_SCREEN_SECURITY_SCREEN_SHARE_OBSERVER_H_
-#define ASH_COMMON_SYSTEM_CHROMEOS_SCREEN_SECURITY_SCREEN_SHARE_OBSERVER_H_
+#ifndef ASH_SYSTEM_SCREEN_SECURITY_SCREEN_SHARE_OBSERVER_H_
+#define ASH_SYSTEM_SCREEN_SECURITY_SCREEN_SHARE_OBSERVER_H_
 
 #include "base/callback.h"
 #include "base/strings/string16.h"
 
 namespace ash {
 
 class ScreenShareObserver {
  public:
   // Called when screen share is started.
   virtual void OnScreenShareStart(const base::Closure& stop_callback,
                                   const base::string16& helper_name) = 0;
 
   // Called when screen share is stopped.
   virtual void OnScreenShareStop() = 0;
 
  protected:
   virtual ~ScreenShareObserver() {}
 };
 
 }  // namespace ash
 
-#endif  // ASH_COMMON_SYSTEM_CHROMEOS_SCREEN_SECURITY_SCREEN_SHARE_OBSERVER_H_
+#endif  // ASH_SYSTEM_SCREEN_SECURITY_SCREEN_SHARE_OBSERVER_H_