- Merged all three BroadcastReceivers into one.
(Changed class name because old ones may have been disabled.)
- Use IntentService to perform the tasks in a worker thread.
Note the new receiver will never be disabled. We always need to start
exchange.SyncManager.
Bug 2722155
Bug 2416929
Change-Id: I8241880fc1ee38d85dcdca7e1d46fc2f6b2d375b