diff -r 000000000000 -r 6474c204b198 dom/filesystem/FileSystemUtils.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dom/filesystem/FileSystemUtils.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,53 @@
+/* -*- Mode: c++; c-basic-offset: 2; indent-tabs-mode: nil; tab-width: 40 -*- */
+/* vim: set ts=2 et sw=2 tw=80: */
+/* 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/. */
+
+#ifndef mozilla_dom_FileSystemUtils_h
+#define mozilla_dom_FileSystemUtils_h
+
+#include "nsString.h"
+
+namespace mozilla {
+namespace dom {
+
+#define FILESYSTEM_DOM_PATH_SEPARATOR "/"
+
+/*
+ * This class is for error handling.
+ * All methods in this class are static.
+ */
+class FileSystemUtils
+{
+public:
+  /*
+   * Convert the path separator to "/".
+   */
+  static void
+  LocalPathToNormalizedPath(const nsAString& aLocal, nsAString& aNorm);
+
+  /*
+   * Convert the normalized path separator "/" to the system dependent path
+   * separator, which is "/" on Mac and Linux, and "\" on Windows.
+   */
+  static void
+  NormalizedPathToLocalPath(const nsAString& aNorm, nsAString& aLocal);
+
+  /*
+   * Return true if aDescendantPath is a descendant of aPath. Both aPath and
+   * aDescendantPath are absolute DOM path.
+   */
+  static bool
+  IsDescendantPath(const nsAString& aPath, const nsAString& aDescendantPath);
+
+  static bool
+  IsParentProcess();
+
+  static const char16_t kSeparatorChar = char16_t('/');
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif // mozilla_dom_FileSystemUtils_h