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

content/child/webcrypto/nss/rsa_key_nss.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/child/webcrypto/nss/rsa_key_nss.h"
 
 #include <secasn1.h>
 
 #include "base/logging.h"
 #include "content/child/webcrypto/crypto_data.h"
@@ skipping 505 matching lines @@
   Status status = CheckKeyCreationUsages(
       all_public_key_usages_ | all_private_key_usages_, combined_usages);
   if (status.IsError())
     return status;
 
   const blink::WebCryptoKeyUsageMask public_usages =
       combined_usages & all_public_key_usages_;
   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(),
                                   &public_exponent,
                                   &modulus_length_bits);
   if (status.IsError())
     return status;
 
   crypto::ScopedPK11Slot slot(PK11_GetInternalKeySlot());
   if (!slot)
@@ skipping 382 matching lines @@
                  key->algorithm().rsaHashedParams()->publicExponent().size())) {
     return Status::ErrorUnexpected();
   }
 
   return Status::Success();
 }
 
 }  // namespace webcrypto
 
 }  // namespace content