Extract IsKnownRoot() functionality for testing if a certificate is a

net/cert/known_roots_mac.h

+// Copyright (c) 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.
+
+#ifndef NET_CERT_KNOWN_ROOTS_MAC_H_
+#define NET_CERT_KNOWN_ROOTS_MAC_H_
+
+#include <Security/Security.h>
+
+namespace net {
+
+// IsKnownRoot returns true if the given certificate is one that we believe
+// is a standard (as opposed to user-installed) root.
+//
+// NOTE: The first call will lazily initialize the known roots, which requires
+// holding crypto::GetMacSecurityServicesLock(). Callers must therefore either
+// acquire that lock prior to calling this, or eagerly initialize beforehand
+// using InitializeKnownRoots().
+bool IsKnownRoot(SecCertificateRef cert);
+
+// Calling this is optional as initialization will otherwise be done lazily when
+// calling IsKnownRoot(). When calling this, the current thread must NOT already
+// be holding/ crypto::GetMacSecurityServicesLock().
+void InitializeKnownRoots();
+
+}  // namespace net
+
+#endif  // NET_CERT_KNOWN_ROOTS_MAC_H_