diff -r 000000000000 -r 6474c204b198 ipc/chromium/src/base/atomicops_internals_mutex.cc
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/ipc/chromium/src/base/atomicops_internals_mutex.cc	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,16 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: sw=2 ts=8 et :
+ */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "base/atomicops.h"
+
+namespace base {
+namespace subtle {
+
+Lock gAtomicsMutex;
+
+}  // namespace subtle
+}  // namespace base