Refactor the interface for generating keys.

content/child/webcrypto/nss/sym_key_nss.h

 // 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.
 
 #ifndef CONTENT_CHILD_WEBCRYPTO_NSS_SYM_KEY_NSS_H_
 #define CONTENT_CHILD_WEBCRYPTO_NSS_SYM_KEY_NSS_H_
 
 #include <pkcs11t.h>
 
 #include "third_party/WebKit/public/platform/WebCrypto.h"
 
 namespace content {
 
 namespace webcrypto {
 
 class CryptoData;
+class GenerateKeyResult;
 class Status;
 
 Status GenerateSecretKeyNss(const blink::WebCryptoKeyAlgorithm& algorithm,
                             bool extractable,
                             blink::WebCryptoKeyUsageMask usage_mask,
                             unsigned keylen_bytes,
                             CK_MECHANISM_TYPE mechanism,
-                            blink::WebCryptoKey* key);
+                            GenerateKeyResult* result);
 
 Status ImportKeyRawNss(const CryptoData& key_data,
                        const blink::WebCryptoKeyAlgorithm& algorithm,
                        bool extractable,
                        blink::WebCryptoKeyUsageMask usage_mask,
                        CK_MECHANISM_TYPE mechanism,
                        CK_FLAGS flags,
                        blink::WebCryptoKey* key);
 
 }  // namespace webcrypto
 
 }  // namespace content
 
 #endif  // CONTENT_CHILD_WEBCRYPTO_NSS_SYM_KEY_NSS_H_