Refactor AccelerometerReader to provide an Observer

ash/accelerometer/accelerometer_controller.h

-// Copyright 2014 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_ACCELEROMETER_ACCELEROMETER_CONTROLLER_H_
-#define ASH_ACCELEROMETER_ACCELEROMETER_CONTROLLER_H_
-
-#include "ash/ash_export.h"
-#include "base/memory/ref_counted.h"
-#include "base/memory/scoped_ptr.h"
-#include "base/observer_list.h"
-
-#if defined(OS_CHROMEOS)
-#include "chromeos/accelerometer/accelerometer_reader.h"
-#endif
-
-namespace base {
-class TaskRunner;
-}
-
-namespace ash {
-
-class AccelerometerObserver;
-
-// This class owns the communication interface for talking to the accelerometer
-// on supporting devices. Observers will be delivered OnAccelerometerRead
-// notifications if an accelerometer was detected.
-class ASH_EXPORT AccelerometerController
-#if defined(OS_CHROMEOS)
-    : public chromeos::AccelerometerReader::Delegate {
-#else
-    {
-#endif
- public:
-  AccelerometerController();
-  virtual ~AccelerometerController();
-
-  // Initialize the accelerometer reader.
-  void Initialize(scoped_refptr<base::TaskRunner> blocking_task_runner);
-
-  // Add/remove observer.
-  void AddObserver(AccelerometerObserver* observer);
-  void RemoveObserver(AccelerometerObserver* observer);
-
-#if defined(OS_CHROMEOS)
-  // This needs to be CHROMEOS only as on other platforms it does not actually
-  // override a method.
-  // chromeos::AccelerometerReader::Delegate:
-  virtual void HandleAccelerometerUpdate(
-      const ui::AccelerometerUpdate& update) override;
-#endif
-
- private:
-#if defined(OS_CHROMEOS)
-  // The AccelerometerReader which directly triggers and reads from the
-  // accelerometer device.
-  scoped_ptr<chromeos::AccelerometerReader> reader_;
-#endif
-
-  ObserverList<AccelerometerObserver, true> observers_;
-
-  DISALLOW_COPY_AND_ASSIGN(AccelerometerController);
-};
-
-}  // namespace ash
-
-#endif  // ASH_ACCELEROMETER_ACCELEROMETER_CONTROLLER_H_