Remove references to the DB thread for pwmgr

BUG=667892
R=vasilii@chromium.org

Change-Id: I914c3d2933ff95b04d7cbf3c346c0e8de127b893
Reviewed-on: https://chromium-review.googlesource.com/584836
Reviewed-by: Vasilii Sukhanov <vasilii@chromium.org>
Commit-Queue: Jochen Eisinger <jochen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#489303}
4 files changed