GitLab

This doesn't do anything yet, mostly adds supporting infrastructure.

R=lliabraa@chromium.org, mark@chromium.org, sdefresne@chromium.org, lliabraa, mark, sdefresne
TBR=darin

BUG=426870

Review URL: https://codereview.chromium.org/669673004

Cr-Commit-Position: refs/heads/master@{#301119}