On service calls to startSync, make sure SyncManager is running

* Check that SyncManager's thread is running when called for startSync;
  if not, start the service via Intent
* Mostly fixes #2133115 (although there are possibly other cases for
  SyncManager not running, this will cause any manual "Refresh" to start
  it up.)
* Added large comment at onCreate to explain how all this works

Change-Id: Ib43211ddb36e2f79ee5b1f6973f8bc2bc499024c
1 file changed