Merge from Widevine repo of http://go/wvgerrit/24241
The CL also only modifies existing tests so that they will pass
with an old version of OEMCrypto, or it filters out the tests so
that they do not run. This positions us so that we can more
easily verify how much backwards compatibility we expect to work.
bug: 35877886
Change-Id: Iadc06672d7f9cef75800662ff83389c504a3fd04