Add battery status to settings row in uber tray bubble.

ash/system/power/tray_power.h

Index: ash/system/power/tray_power.h
diff --git a/ash/system/power/tray_power.h b/ash/system/power/tray_power.h
index 864d14e9d5f4c6f36261e97b6e86da7ff96aa0dc..491d5e8ff03cddc7b579b08245848c7ef00c42fe 100644
--- a/ash/system/power/tray_power.h
+++ b/ash/system/power/tray_power.h
@@ -9,6 +9,12 @@
 #include "ash/system/power/power_status_observer.h"
 #include "ash/system/tray/system_tray_item.h"
 
+class SkBitmap;
+
+namespace gfx {
+class ImageSkia;
+}
+
 namespace ash {
 namespace internal {
 
@@ -17,12 +23,20 @@ class PowerNotificationView;
 class PowerTrayView;
 }
 
+enum IconSet {
+  ICON_LIGHT,
+  ICON_DARK
+};
+
 class TrayPower : public SystemTrayItem,
                   public PowerStatusObserver {
  public:
   TrayPower();
   virtual ~TrayPower();
 
+  static gfx::ImageSkia GetBatteryImage(const PowerSupplyStatus& supply_status,
+                                        IconSet icon_set);
+
  private:
   enum NotificationState {
     NOTIFICATION_NONE,