Screen will appear when user is re-authenticating after a supervision
transition occurs, if ARC++ was enabled when that happened.
Screen will remain visible until transition finishes or times out,
in which case it will clean up all ARC++ data.

Bug: 903851
Change-Id: Ia960355930fba05dd6ffd07b23693690c77b28b1
Reviewed-on: https://chromium-review.googlesource.com/c/1340891
Commit-Queue: Bruno Santos <brunoad@google.com>
Reviewed-by: Jacob Dufault <jdufault@chromium.org>
Reviewed-by: Yury Khmel <khmel@chromium.org>
Reviewed-by: Michael Giuffrida <michaelpg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#615675}