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

content/child/webcrypto/openssl/ec_key_openssl.cc

Index: content/child/webcrypto/openssl/ec_key_openssl.cc
diff --git a/content/child/webcrypto/openssl/ec_key_openssl.cc b/content/child/webcrypto/openssl/ec_key_openssl.cc
index 8d5fc0879d70227c6c687918cb3515dce2b73af4..81e233701f42767301e104023301db12f4942f6f 100644
--- a/content/child/webcrypto/openssl/ec_key_openssl.cc
+++ b/content/child/webcrypto/openssl/ec_key_openssl.cc
@@ -218,6 +218,9 @@ Status EcAlgorithm::GenerateKey(const blink::WebCryptoAlgorithm& algorithm,
   const blink::WebCryptoKeyUsageMask private_usages =
       combined_usages & all_private_key_usages_;
 
+  if (private_usages == 0)
+    return Status::ErrorCreateKeyEmptyUsages();
+
   const blink::WebCryptoEcKeyGenParams* params = algorithm.ecKeyGenParams();
 
   crypto::OpenSSLErrStackTracer err_tracer(FROM_HERE);