GitLab

A couple of pieces are left as TODOs for future CLs:
  * Porting the "seek device by Bluetooth address" feature.
  * Wiring up a screen lock state accessor.

BUG=420946
TEST=components_unittests
R=tengs@chromium.org

Review URL: https://codereview.chromium.org/633253002

Cr-Commit-Position: refs/heads/master@{#299415}