diff -r 000000000000 -r 6474c204b198 dom/system/OSFileConstants.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dom/system/OSFileConstants.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,58 @@
+/* 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_osfileconstants_h__
+#define mozilla_osfileconstants_h__
+
+#include "nsIOSFileConstantsService.h"
+#include "mozilla/Attributes.h"
+
+namespace mozilla {
+
+/**
+ * Perform initialization of this module.
+ *
+ * This function _must_ be called:
+ * - from the main thread;
+ * - before any Chrome Worker is created.
+ *
+ * The function is idempotent.
+ */
+nsresult InitOSFileConstants();
+
+/**
+ * Perform cleanup of this module.
+ *
+ * This function _must_ be called:
+ * - from the main thread;
+ * - after all Chrome Workers are dead.
+ *
+ * The function is idempotent.
+ */
+void CleanupOSFileConstants();
+
+/**
+ * Define OS-specific constants.
+ *
+ * This function creates or uses JS object |OS.Constants| to store
+ * all its constants.
+ */
+bool DefineOSFileConstants(JSContext *cx, JS::Handle<JSObject*> global);
+
+/**
+ * XPConnect initializer, for use in the main thread.
+ */
+class OSFileConstantsService MOZ_FINAL : public nsIOSFileConstantsService
+{
+ public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIOSFILECONSTANTSSERVICE
+  OSFileConstantsService();
+private:
+  ~OSFileConstantsService();
+};
+
+}
+
+#endif // mozilla_osfileconstants_h__