Check key before edit value in countFlushCompleteEventsLocked

Fix an unchecked editValueFor that potentially causes log fatal
when sensor is removed from connection shortly before arrival of
flush complete message.

Bug: 62806749
Test: compiles, flush() still working.
Change-Id: I3684251b7bb746b01d0d8849024217c80ad52f9d
Merged-In: I3684251b7bb746b01d0d8849024217c80ad52f9d
1 file changed