Add battery status to settings row in uber tray bubble.

ash/system/settings/tray_settings.h

Index: ash/system/settings/tray_settings.h
diff --git a/ash/system/settings/tray_settings.h b/ash/system/settings/tray_settings.h
index 18536fe051bfd1006e02dac0599017ec0d60e403..1b9ca97e757439924edf5817afaea603ca6eccb0 100644
--- a/ash/system/settings/tray_settings.h
+++ b/ash/system/settings/tray_settings.h
@@ -6,12 +6,18 @@
 #define ASH_SYSTEM_SETTINGS_TRAY_SETTINGS_H_
 #pragma once
 
+#include "ash/system/power/power_status_observer.h"
 #include "ash/system/tray/system_tray_item.h"
 
 namespace ash {
 namespace internal {
 
-class TraySettings : public SystemTrayItem {
+namespace tray {
+class SettingsDefaultView;
+}
+
+class TraySettings : public SystemTrayItem,
+                     public PowerStatusObserver {
  public:
   TraySettings();
   virtual ~TraySettings();
@@ -26,6 +32,11 @@ class TraySettings : public SystemTrayItem {
   virtual void DestroyDetailedView() OVERRIDE;
   virtual void UpdateAfterLoginStatusChange(user::LoginStatus status) OVERRIDE;
 
+  // Overridden from PowerStatusObserver.
+  virtual void OnPowerStatusChanged(const PowerSupplyStatus& status) OVERRIDE;
+
+  tray::SettingsDefaultView* default_view_;
+
   DISALLOW_COPY_AND_ASSIGN(TraySettings);
 };