Class mock.Mock does not exist method "called_once_with()", it just
exists method "assert_called_once_with()". "called_once_with()" does
nothing because it's a mock object.
In OSC, only one place is still using "called_once_with()". Fix it.
Change-Id: Ib890e95d775c3fc43df80fa05c82d726e78cdac8
Partial Bug: 1544522