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

content/child/webcrypto/openssl/sym_key_openssl.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/openssl/sym_key_openssl.h"
 
 #include <vector>
 #include <openssl/rand.h>
 
 #include "content/child/webcrypto/crypto_data.h"
@@ skipping 14 matching lines @@
                                 GenerateKeyResult* result) {
   crypto::OpenSSLErrStackTracer err_tracer(FROM_HERE);
 
   std::vector<unsigned char> random_bytes(keylen_bytes, 0);
 
   if (keylen_bytes > 0) {
     if (!(RAND_bytes(&random_bytes[0], keylen_bytes)))
       return Status::OperationError();
   }
 
+  if (usages == 0) {

[eroman, 2014/11/20 23:40:10]

Move this higher up -- should fail fast before doing the work of key generation.

[nharper, 2014/11/21 22:12:01]

Done.

+    return Status::ErrorCreateKeyBadUsages();
+  }
+
   result->AssignSecretKey(
       blink::WebCryptoKey::create(new SymKeyOpenSsl(CryptoData(random_bytes)),
                                   blink::WebCryptoKeyTypeSecret,
                                   extractable,
                                   algorithm,
                                   usages));
 
   return Status::Success();
 }
 
 Status ImportKeyRawOpenSsl(const CryptoData& key_data,
                            const blink::WebCryptoKeyAlgorithm& algorithm,
                            bool extractable,
                            blink::WebCryptoKeyUsageMask usages,
                            blink::WebCryptoKey* key) {
   *key = blink::WebCryptoKey::create(new SymKeyOpenSsl(key_data),
                                      blink::WebCryptoKeyTypeSecret,
                                      extractable,
                                      algorithm,
                                      usages);
   return Status::Success();
 }
 
 }  // namespace webcrypto
 
 }  // namespace content