Convert //ash from scoped_ptr to std::unique_ptr

ash/keyboard/keyboard_ui_observer.h

 // Copyright 2016 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_KEYBOARD_KEYBOARD_UI_OBSERVER_H_
 #define ASH_KEYBOARD_KEYBOARD_UI_OBSERVER_H_
 
 #include "ash/ash_export.h"
 #include "base/macros.h"
-#include "base/memory/scoped_ptr.h"
 
 namespace ash {
 
 class ASH_EXPORT KeyboardUIObserver {
  public:
   virtual void OnKeyboardEnabledStateChanged(bool new_value) = 0;
 
  protected:
   virtual ~KeyboardUIObserver() {}
 };
 
 }  // namespace ash
 
 #endif  // ASH_KEYBOARD_KEYBOARD_UI_OBSERVER_H_