Don't enable calendar sync if sync_events is disabled

* When SyncManager starts up, it reconciles the AccountManager sync settings
  with its own
* This works for Contacts, but Calendar has a second setting that needs to be
  checked - the sync_events column in the Calendar table (in CalendarProvider2)
* Before turning on Calendar sync, we now check this second setting; if
  sync_events is 0, we won't re-enable Calendar sync

Bug: 2619755
Change-Id: Iea6c99dce228d2c111a529a6c9b865ed1577b19e
1 file changed