Merge from widevine repo of http://go/wvgerrit/16250
The verification string in the key control block has an obvious
pattern that is incremented every time we update the API. This CL
adds a unit test to make sure an implementation of OEMCrypto is not
casually accepting a future version of the key control block before
the API has even been defined.
Change-Id: I3f837f7346ef7de399441f5fcda9b13b65fa51f4
a99825b7aa