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

ash/system/brightness_control_delegate.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_SYSTEM_BRIGHTNESS_CONTROL_DELEGATE_H_
-#define ASH_SYSTEM_BRIGHTNESS_CONTROL_DELEGATE_H_
-
-#include "base/callback.h"
-
-namespace ui {
-class Accelerator;
-}  // namespace ui
-
-namespace ash {
-
-// Delegate for controlling the brightness.
-class BrightnessControlDelegate {
- public:
-  virtual ~BrightnessControlDelegate() {}
-
-  // Handles an accelerator-driven request to decrease or increase the screen
-  // brightness.
-  virtual void HandleBrightnessDown(const ui::Accelerator& accelerator) = 0;
-  virtual void HandleBrightnessUp(const ui::Accelerator& accelerator) = 0;
-
-  // Requests that the brightness be set to |percent|, in the range
-  // [0.0, 100.0].  |gradual| specifies whether the transition to the new
-  // brightness should be animated or instantaneous.
-  virtual void SetBrightnessPercent(double percent, bool gradual) = 0;
-
-  // Asynchronously invokes |callback| with the current brightness, in the range
-  // [0.0, 100.0].
-  virtual void GetBrightnessPercent(
-      const base::Callback<void(double)>& callback) = 0;
-};
-
-}  // namespace ash
-
-#endif  // ASH_SYSTEM_BRIGHTNESS_CONTROL_DELEGATE_H_