Move low battery notification to Message Center.

ash/system/chromeos/settings/tray_settings.cc

Index: ash/system/chromeos/settings/tray_settings.cc
diff --git a/ash/system/chromeos/settings/tray_settings.cc b/ash/system/chromeos/settings/tray_settings.cc
index c7f9039e1fcb4498f6eea057265c7c417ad12a40..f8325ec3db8b09162afdb00867ae221675aa2444 100644
--- a/ash/system/chromeos/settings/tray_settings.cc
+++ b/ash/system/chromeos/settings/tray_settings.cc
@@ -64,8 +64,7 @@ class SettingsDefaultView : public ActionableView,
     }
 
     if (PowerStatus::Get()->IsBatteryPresent()) {
-      power_status_view_ = new ash::PowerStatusView(
-          ash::PowerStatusView::VIEW_DEFAULT, power_view_right_align);
+      power_status_view_ = new ash::PowerStatusView(power_view_right_align);
       AddChildView(power_status_view_);
       OnPowerStatusChanged();
     }