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

content/public/browser/battery_status_provider.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_PUBLIC_BROWSER_BATTERY_STATUS_PROVIDER_H_
+#define CONTENT_PUBLIC_BROWSER_BATTERY_STATUS_PROVIDER_H_
+
+#include <list>
+
+#include "base/memory/singleton.h"
+#include "base/observer_list.h"
+#include "content/common/content_export.h"
+
+namespace content {
+
+struct CONTENT_EXPORT PowerSupplyStatus {
+  bool line_power_on;
+
+  bool battery_is_present;
+  bool battery_is_full;
+
+  // Time in seconds until the battery is empty or full, 0 for unknown.
+  int64 battery_seconds_to_empty;
+  int64 battery_seconds_to_full;
+
+  double battery_percentage;
+
+  bool is_calculating_battery_time;
+};
+
+class CONTENT_EXPORT BatteryStatusProvider {
+ public:
+  class CONTENT_EXPORT Observer {
+   public:
+    virtual void PowerChanged(const PowerSupplyStatus& power_status) = 0;
+  };
+
+  static BatteryStatusProvider* GetInstance();
+
+  void AddObserver(Observer* observer);
+  void RemoveObserver(Observer* observer);
+
+  // Sends updated battery status information to all the observers.
+  void SendUpdate(const PowerSupplyStatus& power_status);
+
+ private:
+  friend struct DefaultSingletonTraits<BatteryStatusProvider>;
+
+  BatteryStatusProvider();
+  virtual ~BatteryStatusProvider();
+
+  ObserverList<Observer> observers_;
+
+  DISALLOW_COPY_AND_ASSIGN(BatteryStatusProvider);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_PUBLIC_BROWSER_BATTERY_STATUS_PROVIDER_H_