Fix a sync problem in NativeDaemonConnector.

We had a gap in sync coverage between doing a check and waiting and a
matching gap between setting a condition and notifying.  It was possible
to get context switched just so and have the notify hit before the waiter
had started waiting.

bug:6492166
Change-Id: Idc876cf85b35902a79fae932547957ed5ef00e4f