Backwards Compatibility Tests

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

libwvdrmengine/oemcrypto/test/oec_session_util.h

@@ -203,6 +203,13 @@ class Session {
   void TestDecryptCTR(bool select_key_first = true,
                       OEMCryptoResult expected_result = OEMCrypto_SUCCESS,
                       int key_index = 0);
+  // This compares the actual result with the expected result.  If OEMCrypto is
+  // an older version, we allow it to report an equivalent error code.
+  void TestDecryptResult(OEMCryptoResult expected_result,
+                         OEMCryptoResult actual_result);
+  // Verify that an attempt to select an expired key either succeeds, or gives
+  // an actionable error code.
+  void TestSelectExpired(unsigned int key_index);
   // Calls OEMCrypto_GetOEMPublicCertificate and loads the OEM cert's public
   // rsa key into public_rsa_.
   void LoadOEMCert(bool verify_cert = false);