Use SecKeyCreateSignature on macOS 10.12 and later.

net/ssl/ssl_private_key_test_util.h

+// Copyright 2016 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 NET_SSL_SSL_PRIVATE_KEY_TEST_UTIL_H_
+#define NET_SSL_SSL_PRIVATE_KEY_TEST_UTIL_H_
+
+#include <string>
+
+#include "net/ssl/ssl_private_key.h"
+
+namespace net {
+
+const char* SSLPrivateKeyTypeToString(SSLPrivateKey::Type type);
+
+// Tests that |key| matches the private key serialized in |pkcs8|. It checks the
+// reported type and key size are correct, and then it tests all advertised
+// signature algorithms align with |pkcs8|. It does not test unadvertised
+// algorithms, so the caller must check this list is as expected.
+void TestSSLPrivateKeyMatches(SSLPrivateKey* key, const std::string& pkcs8);
+
+}  // namespace net
+
+#endif  // NET_SSL_SSL_PRIVATE_KEY_TEST_UTIL_H_