GitLab

User Interface document was moved into Apps during merge.
This update moves it under Extensions.

Bug: None
Change-Id: Ic7a3f53ac24f3b4949940eb237cb572d3420202f
Reviewed-on: https://chromium-review.googlesource.com/996237Reviewed-by: Meggin Kearney <mkearney@chromium.org>
Commit-Queue: Crystal Lambert <crystallambert@chromium.org>
Cr-Commit-Position: refs/heads/master@{#548129}