DO NOT MERGE Fix null pointer exception when updating rotation tile. (Bug 11111473)

This occurs when switching users on devices that
don't have a rotation lock quick settings tile.

Change-Id: I738ca15ca754be90cec7eaf3a8eda3e38ed96b33
(cherry picked from commit e8f50a1400)

packages/SystemUI/src/com/android/systemui/statusbar/phone/QuickSettingsModel.java

@@ -280,7 +280,7 @@ class QuickSettingsModel implements BluetoothStateChangeCallback,
         mUserTracker = new CurrentUserTracker(mContext) {
             public void onUserSwitched(int newUserId) {
                 mBrightnessObserver.startObserving();
-                onRotationLockChanged();
+                refreshRotationLockTile();
                 onBrightnessLevelChanged();
                 onNextAlarmChanged();
                 onBugreportChanged();