Prepare to replace windows across recreate().

When the activity locally recreates itself, nothing
on the server side is able to prepare preserving windows,
or replacing windows. The activity was trying to defer
removing the old window, but it was just waiting
until the new one was created, not until it was drawn,
thus resulting in a flicker. It's easy to backpack on the
existing replacement infrastructure.

Bug: 28221875
Change-Id: I55fc4ca78e9e11809473fedd8b30b6a6350cf852