OSCrypt for POSIX uses libsecret to store a randomised encryption key.

components/os_crypt/key_storage_linux.cc

+// 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.
+
+#include "components/os_crypt/key_storage_linux.h"
+
+#include "components/os_crypt/key_storage_libsecret.h"
+
+// static
+std::unique_ptr<KeyStorageLinux> KeyStorageLinux::CreateService() {
+  std::unique_ptr<KeyStorageLinux> key_storage(new KeyStorageLibsecret());
+
+  if (key_storage->Init())
+    return key_storage;
+
+  return nullptr;
+}