Add X509CertificateBytes which uses CRYPTO_BUFFER instead of macOS-native certificate types.

net/cert/x509_util_ios.cc

+// Copyright 2017 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 "net/cert/x509_util_ios.h"
+
+#include "net/cert/x509_certificate.h"
+
+namespace net {
+
+namespace x509_util {
+
+base::ScopedCFTypeRef<SecCertificateRef>
+CreateSecCertificateFromX509Certificate(const X509Certificate* cert) {
+  return base::ScopedCFTypeRef<SecCertificateRef>(
+      reinterpret_cast<SecCertificateRef>(
+          const_cast<void*>(CFRetain(cert->os_cert_handle()))));
+}
+
+}  // namespace x509_util
+
+}  // namespace net