mash: Migrate [Keyboard]Brightness code to ash/common.

ash/system/keyboard_brightness/keyboard_brightness_control_delegate.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 ASH_SYSTEM_KEYBOARD_BRIGHTNESS_KEYBOARD_BRIGHTNESS_CONTROL_DELEGATE_H_
-#define ASH_SYSTEM_KEYBOARD_BRIGHTNESS_KEYBOARD_BRIGHTNESS_CONTROL_DELEGATE_H_
-
-namespace ui {
-class Accelerator;
-}  // namespace ui
-
-namespace ash {
-
-// Delegate for controlling the keyboard brightness.
-class KeyboardBrightnessControlDelegate {
- public:
-  virtual ~KeyboardBrightnessControlDelegate() {}
-
-  // Handles an accelerator-driven request to decrease or increase the keyboard
-  // brightness.
-  virtual void HandleKeyboardBrightnessDown(
-      const ui::Accelerator& accelerator) = 0;
-  virtual void HandleKeyboardBrightnessUp(
-      const ui::Accelerator& accelerator) = 0;
-};
-
-}  // namespace ash
-
-#endif  // ASH_SYSTEM_KEYBOARD_BRIGHTNESS_KEYBOARD_BRIGHTNESS_CONTROL_DELEGATE_H_