Fix auto-pip visibility issues.

In the case that we defer stop for auto-enter picture
in picture, we should also defer changing the visibility. This causes
particularly awkward issues with SurfaceView as the views are left
in a severed state.

Test: Auto-pip Chrome from youtube. Things look alright!
Bug: 36355266
Bug: 36640131
Change-Id: I77de1c3eb9c61b03740cbe49f88dec1af2ed6577