Generate nonce before signing fake license request

Merge from: http://go/wvgerrit/160557

Bug: 242100344
Test: tested with http://go/ag/20420224

Change-Id: I35f625998f04a728f950075cc200e15f93dfb474

libwvdrmengine/cdm/core/src/cdm_session.cpp

@@ -307,8 +307,11 @@ CdmResponseType CdmSession::RestoreOfflineSession(const CdmKeySetId& key_set_id,
     std::string fake_message("empty message");
     std::string core_message;
     std::string license_request_signature;
+    uint32_t nonce;
     // Sign a fake message so that OEMCrypto will start the rental clock. The
     // signature and generated core message are ignored.
+    result = crypto_session_->GenerateNonce(&nonce);
+    if (result != NO_ERROR) return result;
     result = crypto_session_->PrepareAndSignLicenseRequest(
         fake_message, &core_message, &license_request_signature);
     if (result != NO_ERROR) return result;