GitLab

- Also fixed in FocusPreviousUser
- Add unit test to validate crash does not regress

Bug: 895589
Change-Id: Ibb436d95b558089d36a8b10f33fab2bc88568214
Reviewed-on: https://chromium-review.googlesource.com/c/1320212Reviewed-by: Quan Nguyen <qnnguyen@chromium.org>
Commit-Queue: Jacob Dufault <jdufault@chromium.org>
Cr-Commit-Position: refs/heads/master@{#605811}