Merge from Widevine repo of http://go/wvgerrit/56760
This CL backs out one restriction added in http://go/wvgerrit/42941.
In that CL, a sample would not be processed if the policy engine says
the key cannot be used for a given security level. The change relaxes
the check and does not run the verification if the sample is clear.
Bug: 112113797
Bug: 115758660
Test: GTS tests. Unit tests. Verified Play movies and Netflix.
Test: version number unit tests fail as expected.
Change-Id: I5238745c3d3d7f0eb7fae203f4579e8df4d0681b