chromeos: Add support for the battery status API on chromeos.

content/browser/battery_status/battery_status_provider_impl.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 CONTENT_BROWSER_BATTERY_STATUS_BATTERY_STATUS_PROVIDER_IMPL_H_
+#define CONTENT_BROWSER_BATTERY_STATUS_BATTERY_STATUS_PROVIDER_IMPL_H_
+
+#include "base/memory/singleton.h"
+#include "base/observer_list.h"
+#include "content/public/browser/battery_status_provider.h"
+
+namespace content {
+
+class BatteryStatusProviderImpl : public BatteryStatusProvider {
+ public:
+  class Observer {
+   public:
+    virtual void PowerChanged(const PowerSupplyStatus& power_status) = 0;
+  };
+
+  static BatteryStatusProviderImpl* GetInstance();
+
+  void AddObserver(Observer* observer);
+  void RemoveObserver(Observer* observer);
+
+  // Overridden from BatteryStatusProvider.
+  virtual void SendUpdate(const PowerSupplyStatus& power_status) OVERRIDE;
+
+ private:
+  friend struct DefaultSingletonTraits<BatteryStatusProviderImpl>;
+
+  BatteryStatusProviderImpl();
+  virtual ~BatteryStatusProviderImpl();
+
+  ObserverList<Observer> observers_;
+
+  DISALLOW_COPY_AND_ASSIGN(BatteryStatusProviderImpl);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_BATTERY_STATUS_BATTERY_STATUS_PROVIDER_IMPL_H_