GitLab

This is a reland of c618b6e7

Original change's description:
> Add skeleton of Demo Mode setup UI.
>
> Mocks:
> https://gallery.googleplex.com/projects/MCHbtQVoQ2HCZeqwFvuvKaZQ/files/MCGxzIhEyEZFkDOfw1G1Tu4Z
>
> Bug: 827376
> Cq-Include-Trybots: luci.chromium.try:closure_compilation
> Change-Id: I1206687fff441ec6be5a3bb9e6dddba7469f292b
> Reviewed-on: https://chromium-review.googlesource.com/1100237
> Commit-Queue: Aga Wronska <agawronska@chromium.org>
> Reviewed-by: Michael Giuffrida <michaelpg@chromium.org>
> Reviewed-by: Alexander Alekseev <alemate@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#571137}

Bug: 827376
Change-Id: I8f4d81e2e10437b23cd4c84eac95204600fb28ee
Cq-Include-Trybots: luci.chromium.try:closure_compilation
Reviewed-on: https://chromium-review.googlesource.com/1119268Reviewed-by: Alexander Alekseev <alemate@chromium.org>
Commit-Queue: Aga Wronska <agawronska@chromium.org>
Cr-Commit-Position: refs/heads/master@{#571659}