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

ash/system/chromeos/keyboard_brightness_controller.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_CHROMEOS_KEYBOARD_BRIGHTNESS_CONTROLLER_H_
-#define ASH_SYSTEM_CHROMEOS_KEYBOARD_BRIGHTNESS_CONTROLLER_H_
-
-#include "ash/ash_export.h"
-#include "ash/system/keyboard_brightness/keyboard_brightness_control_delegate.h"
-#include "base/compiler_specific.h"
-#include "base/macros.h"
-
-namespace ash {
-
-// A class which controls keyboard brightness when Alt+F6, Alt+F7 or a
-// multimedia key for keyboard brightness is pressed.
-class ASH_EXPORT KeyboardBrightnessController
-    : public KeyboardBrightnessControlDelegate {
- public:
-  KeyboardBrightnessController() {}
-  ~KeyboardBrightnessController() override {}
-
- private:
-  // Overridden from KeyboardBrightnessControlDelegate:
-  void HandleKeyboardBrightnessDown(
-      const ui::Accelerator& accelerator) override;
-  void HandleKeyboardBrightnessUp(const ui::Accelerator& accelerator) override;
-
-  DISALLOW_COPY_AND_ASSIGN(KeyboardBrightnessController);
-};
-
-}  // namespace ash
-
-#endif  // ASH_SYSTEM_CHROMEOS_KEYBOARD_BRIGHTNESS_CONTROLLER_H_