Check that usage isn't empty when generateKey() is called

content/child/webcrypto/nss/rsa_key_nss.cc

Index: content/child/webcrypto/nss/rsa_key_nss.cc
diff --git a/content/child/webcrypto/nss/rsa_key_nss.cc b/content/child/webcrypto/nss/rsa_key_nss.cc
index 129d5e42b3b845f0abfca4bd49a2ebad74276b6d..42062761a185db5306e9d45f6d652759495cb5bb 100644
--- a/content/child/webcrypto/nss/rsa_key_nss.cc
+++ b/content/child/webcrypto/nss/rsa_key_nss.cc
@@ -523,6 +523,9 @@ Status RsaHashedAlgorithm::GenerateKey(
   const blink::WebCryptoKeyUsageMask private_usages =
       combined_usages & all_private_key_usages_;
 
+  if (private_usages == 0)
+    return Status::ErrorCreateKeyEmptyUsages();
+
   unsigned int public_exponent = 0;
   unsigned int modulus_length_bits = 0;
   status = GetRsaKeyGenParameters(algorithm.rsaHashedKeyGenParams(),