[Mac] Add option to reauthenticate the OS user before revealing passwords.

chrome/browser/password_manager/password_manager_util.h

+// Copyright (c) 2013 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 CHROME_BROWSER_PASSWORD_MANAGER_PASSWORD_MANAGER_UTIL_H_
+#define CHROME_BROWSER_PASSWORD_MANAGER_PASSWORD_MANAGER_UTIL_H_
+
+namespace password_manager_util {
+
+// Attempts to (re-)authenticate the user of the OS account. Returns true if
+// the user was successfully authenticated, or if authentication was not
+// possible. On platforms where reauthentication is not possible or does not
+// make sense, the default implementation always returns true.
+bool AuthenticateUser();
+
+}  // namespace password_manager_util
+
+#endif  // CHROME_BROWSER_PASSWORD_MANAGER_PASSWORD_MANAGER_UTIL_H_