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 "content/common/content_export.h"
+
+namespace content {
+
+struct PowerSupplyStatus;
+
+class CONTENT_EXPORT BatteryStatusProvider {
+ public:
+  static BatteryStatusProvider* GetInstance();
+
+  // Sends updated battery status information to all the observers.
+  virtual void SendUpdate(const PowerSupplyStatus& power_status) = 0;
+
+ protected:
+  virtual ~BatteryStatusProvider() {}
+};
+
+}  // namespace content
+
+#endif  // CONTENT_PUBLIC_BROWSER_BATTERY_STATUS_PROVIDER_H_