Workaround for IllegalArgumentException in SyncManager

* There is a race condition in which the AccountManager listener
  isn't properly unregistered when SyncManager is shut down
* In this case, SyncManager tries to register a new listener
  (i.e. registering again), which causes an IllegalArgumentException
* The quick workaround is simply to catch and ignore this exception,
  as it's really more of a warning than a true error
* A bug will be filed for the underlying issue

Bug: 2631561
Change-Id: I139d24ae045d402d4d8cb006406ef96ccc768566
1 file changed