GitLab

As a first (baby) step of removing the old signin APIs from Sync.

Bug: 825190
Change-Id: I1554c96c54555083f06963a72d2c38248afeb960
Reviewed-on: https://chromium-review.googlesource.com/978186Reviewed-by: Colin Blundell <blundell@chromium.org>
Commit-Queue: Marc Treib <treib@chromium.org>
Cr-Commit-Position: refs/heads/master@{#546065}