Add empty header to fix internal project.
BUG=None
TBR=tommi@webrtc.org
Review-Url: https://codereview.webrtc.org/2790493006
Cr-Commit-Position: refs/heads/master@{#17492}
diff --git a/webrtc/system_wrappers/include/critical_section_wrapper.h b/webrtc/system_wrappers/include/critical_section_wrapper.h
new file mode 100644
index 0000000..5987dce
--- /dev/null
+++ b/webrtc/system_wrappers/include/critical_section_wrapper.h
@@ -0,0 +1,12 @@
+/*
+ * Copyright 2017 The WebRTC Project Authors. All rights reserved.
+ *
+ * Use of this source code is governed by a BSD-style license
+ * that can be found in the LICENSE file in the root of the source
+ * tree. An additional intellectual property rights grant can be found
+ * in the file PATENTS. All contributing project authors may
+ * be found in the AUTHORS file in the root of the source tree.
+ */
+#ifndef WEBRTC_SYSTEM_WRAPPERS_INCLUDE_CRITICAL_SECTION_WRAPPER_H_
+#define WEBRTC_SYSTEM_WRAPPERS_INCLUDE_CRITICAL_SECTION_WRAPPER_H_
+#endif // WEBRTC_SYSTEM_WRAPPERS_INCLUDE_CRITICAL_SECTION_WRAPPER_H_
