Smart Lock: Only add observer to ProximityMonitor once.

ProximityMonitor::AddObserver was previously being called
multiple times. Its mirror RemoveObserver call was also
never called; this CL adds that call. Finally, the
proximity_monitor_ object was being created multiple times
for no reason; now it is created once.

Bug: 910769
Change-Id: If1ab0216d364831cad2bf0d39516af31aa34cbd4
Reviewed-on: https://chromium-review.googlesource.com/c/1367084
Commit-Queue: Ryan Hansberry <hansberry@chromium.org>
Reviewed-by: Kyle Horimoto <khorimoto@chromium.org>
Cr-Commit-Position: refs/heads/master@{#614589}
1 file changed