Merge changes Ie75ef932,I424f96e2,Ieed66079,Ieee4b442,I3c94c963 into udc-dev

* changes:
  [Central Surfaces] Make ShadeHeaderController a singleton.
  [Central Surfaces] Make shade privacy chip & status icons singletons.
  [Central Surfaces] Make shade BatteryMeterView(&Controller) a singleton.
  [Central Surfaces] Make CombinedShadeHeadersConstraintManager singleton.
  [Central Surfaces] Make the shade header view a singleton.