GitLab

Replace it's usages (in tests) with a new KioskAppManagerObserver
method.

BUG=None

Change-Id: I45b569ed23bc69ac0d4888959769828453b3ed3d
Reviewed-on: https://chromium-review.googlesource.com/862242Reviewed-by: Scott Violet <sky@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Commit-Queue: Toni Barzic <tbarzic@chromium.org>
Cr-Commit-Position: refs/heads/master@{#530699}