Implement provisioning 3.0 functionality in oemcrypto mock

Merge from widevine repo of http://go/wvgerrit/21684

This CL adds provisioning 3.0 functionality to the OEMCrypto reference
implementation.

Change-Id: I60c1fd88f246d443e0ae59ad56862c2ea9d95445

libwvdrmengine/oemcrypto/mock/src/oemcrypto_engine_device_properties_cert.cpp

@@ -41,6 +41,17 @@ bool CryptoEngine::supports_keybox() {
   return false;
 }
 
+// This version uses a baked in DRM certificate.
+OEMCrypto_ProvisioningMethod CryptoEngine::provisioning_method() {
+  return OEMCrypto_DrmCertificate;
+}
+
+OEMCryptoResult CryptoEngine::get_oem_certificate(SessionContext *session,
+                                                  uint8_t *public_cert,
+                                                  size_t *public_cert_length) {
+  return OEMCrypto_ERROR_NOT_IMPLEMENTED;
+}
+
 // Returns true to indicate the client does support anti-rollback hardware.
 bool CryptoEngine::is_anti_rollback_hw_present() {
   return false;