GitLab

A bit ugly, but mostly functional. I think most changes going forward
should be aesthetic, so this seems like a decent place for an initial
commit.

Enabled with --ash-enable-window-cycle-ui flag.

BUG=626111

Review-Url: https://codereview.chromium.org/2129773002
Cr-Commit-Position: refs/heads/master@{#406120}