Pausable Object Cleanup - Lock

Lock doesn't need to be a pausable object since it doesn't use any
PausableObject behaviour and can just be a ContextLifecycleObserver.

BUG=907125

Change-Id: If2914dbef4e763f928877294f309ad65ad9da377
Reviewed-on: https://chromium-review.googlesource.com/c/1387163
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Reviewed-by: Alexander Timin <altimin@chromium.org>
Commit-Queue: Dave Tapuska <dtapuska@chromium.org>
Cr-Commit-Position: refs/heads/master@{#618554}
2 files changed