QS: Update embedded vol panel when re-attached to window.

We intentionally drop interim updates when the panel is not
visible, but we should catch up when it becomes visible again.

Not a problem for the dialog panel, since it is torn down / recreated
each time.

Bug:15573750
Change-Id: I717b5d459acb25f9610222e9913d7b8eb71cdd00
1 file changed