Refactor the interface for generating keys.

content/child/webcrypto/openssl/sym_key_openssl.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_OPENSSL_SYM_KEY_OPENSSL_H_
 #define CONTENT_CHILD_WEBCRYPTO_OPENSSL_SYM_KEY_OPENSSL_H_
 
 #include "third_party/WebKit/public/platform/WebCrypto.h"
 
 namespace content {
 
 namespace webcrypto {
 
 class CryptoData;
+class GenerateKeyResult;
 class Status;
 
 Status GenerateSecretKeyOpenSsl(const blink::WebCryptoKeyAlgorithm& algorithm,
                                 bool extractable,
                                 blink::WebCryptoKeyUsageMask usage_mask,
                                 unsigned keylen_bytes,
-                                blink::WebCryptoKey* key);
+                                GenerateKeyResult* result);
 
 Status ImportKeyRawOpenSsl(const CryptoData& key_data,
                            const blink::WebCryptoKeyAlgorithm& algorithm,
                            bool extractable,
                            blink::WebCryptoKeyUsageMask usage_mask,
                            blink::WebCryptoKey* key);
 
 }  // namespace webcrypto
 
 }  // namespace content
 
 #endif  // CONTENT_CHILD_WEBCRYPTO_OPENSSL_SYM_KEY_OPENSSL_H_