[Chromecast] Remove usage of nonreentrant functions.

chromecast/base/file_utils.h

+// 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.
+
+#ifndef CHROMECAST_BASE_FILE_UTILS_H_
+#define CHROMECAST_BASE_FILE_UTILS_H_
+
+#include "base/files/file_path.h"
+
+namespace chromecast {
+
+// Used for locking/unlocking files. This is a blocking request. If the
+// function returns false, this indicates that either the file specified by
+// |path| does not exist, or the locking procedure failed.
+bool LockFile(const base::FilePath& path);
+bool UnlockFile(const base::FilePath& path);
+
+}  // namespace chromecast
+
+#endif  // CHROMECAST_BASE_FILE_UTILS_H_