(This is a merge of http://go/wvgerrit/139569.)
The unit test for DeviceFiles previously had to work around googlemock's
lack of support for move-only types. Now that we have upgraded to
googletest 1.10, we can use move-only types directly via the ByMove()
utility, removing the need for this workaround.
Bug: 207693599
Test: x86-64
Change-Id: Ib4dcc5ec367ef413465a3e8a8f45f9187976ed5e