Fall back to L3 if L1 has test keybox

Merge from Widevine repo of http://go/wvgerrit/142150 (part 2)

For an EVT device, without a keybox or with a test keybox, we want it
to fall back to L3. However, when running the unit or integration
tests it should continue running tests with test keybox. This will
allow us to test L1 oemcrypto on an EVT device, while still using an
EVT device for dogfooding video content at the L3 level.

Bug: 210807585
Bug: 210823889
Change-Id: I30c35134239db35bb39f11f75220063181987763

libwvdrmengine/cdm/core/include/cdm_engine.h

@@ -309,6 +309,12 @@ class CdmEngine {
     return CryptoSession::SetDebugIgnoreKeyboxCount(count);
   }
 
+  // This tells the OEMCrypto adapter to allow the device to continue with a
+  // test keybox. Otherwise, the keybox is reported as invalid.
+  static CdmResponseType SetAllowTestKeybox(bool allow) {
+    return CryptoSession::SetAllowTestKeybox(allow);
+  }
+
   static CdmResponseType ParseDecryptHashString(const std::string& hash_string,
                                                 CdmSessionId* id,
                                                 uint32_t* frame_number,