Run activity visibility adjustment even if there is no top running.

Ensuring visibility is triggered in unpredictable fashion, e.g. it can
be triggered by attachment of application. It can happen between an
activity stopping due to change of user, but before that operation is
finished and as a result the stopped activity will get marked as
visible even if we mark it as invisible in stop. Instead of trying the
activity as invisbile during stopping, we adjust the visibility ensuring
method to go through stack contents even if there is no top running
activity (because the top running activity is run by a different user)
and force the correct visibility.

Bug: 25958227

Change-Id: I4662667e8151fa25d947bacf33ba915389dd32e8