GitLab

I'm dumb and took a while to figure this out so I wrote the
documentation that would have helped.

Change-Id: I18c5cf21225967d2ba496b6b05acdbb3dc9615db
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2065593
Auto-Submit: Adam Langley <agl@chromium.org>
Commit-Queue: Andrew Grieve <agrieve@chromium.org>
Reviewed-by: Andrew Grieve <agrieve@chromium.org>
Cr-Commit-Position: refs/heads/master@{#742946}