Check-in rlz code to src\rlz from http://code.google.com/p/rlz/.

rlz/win/lib/lib_mutex.h

Index: rlz/win/lib/lib_mutex.h
===================================================================
--- rlz/win/lib/lib_mutex.h	(revision 0)
+++ rlz/win/lib/lib_mutex.h	(revision 0)
@@ -0,0 +1,28 @@
+// Copyright (c) 2012 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.
+//
+// Mutex to guarantee serialization of RLZ key accesses.
+
+#ifndef RLZ_WIN_LIB_LIB_MUTEX_H_
+#define RLZ_WIN_LIB_LIB_MUTEX_H_
+
+#include <windows.h>
+
+namespace rlz_lib {
+
+class LibMutex {
+ public:
+  LibMutex();
+  ~LibMutex();
+
+  bool failed(void) { return !acquired_; }
+
+ private:
+  bool acquired_;
+  HANDLE mutex_;
+};
+
+}  // namespace rlz_lib
+
+#endif  // RLZ_WIN_LIB_LIB_MUTEX_H_