Add battery status to settings row in uber tray bubble.

ash/system/tray/system_tray.h

Index: ash/system/tray/system_tray.h
diff --git a/ash/system/tray/system_tray.h b/ash/system/tray/system_tray.h
index 650799ae780f78964065c9a01fd937ddc6a11302..9e5bf74eb73b8702993cae45331907b5127ef5a6 100644
--- a/ash/system/tray/system_tray.h
+++ b/ash/system/tray/system_tray.h
@@ -7,6 +7,7 @@
 #pragma once
 
 #include "ash/ash_export.h"
+#include "ash/system/power/power_supply_status.h"
 #include "ash/system/tray/tray_background_view.h"
 #include "ash/system/tray/tray_views.h"
 #include "ash/system/user/login_status.h"
@@ -96,6 +97,8 @@ class ASH_EXPORT SystemTray : public internal::TrayBackgroundView {
   // Updates the items when the shelf alignment changes.
   void UpdateAfterShelfAlignmentChange(ShelfAlignment alignment);
 
+  void NotifyPowerStatusChange(const PowerSupplyStatus& power_status);
+
   // Returns true if the launcher should show.
   bool should_show_launcher() const {
     return bubble_.get() && should_show_launcher_;
@@ -222,6 +225,7 @@ class ASH_EXPORT SystemTray : public internal::TrayBackgroundView {
   LocaleObserver* locale_observer_;
   NetworkObserver* network_observer_;
   PowerStatusObserver* power_status_observer_;
+  std::vector<PowerStatusObserver*> power_status_observers_;

[stevenjb, 2012/06/07 01:31:18]

Do we need both power_status_observer_ and power_status_observers_?
Also, for consistency with other code, I think we probably want to use
ObserverList and FOR_EACH_OBSERVER.

[jennyz, 2012/06/07 22:06:52]

Done.

   UpdateObserver* update_observer_;
   UserObserver* user_observer_;