diff -r 000000000000 -r 6474c204b198 dom/ipc/PermissionMessageUtils.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dom/ipc/PermissionMessageUtils.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,40 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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_permission_message_utils_h__
+#define mozilla_dom_permission_message_utils_h__
+
+#include "ipc/IPCMessageUtils.h"
+#include "nsCOMPtr.h"
+#include "nsIPrincipal.h"
+
+namespace IPC {
+
+class Principal {
+  friend struct ParamTraits<Principal>;
+
+public:
+  Principal() : mPrincipal(nullptr) {}
+  Principal(nsIPrincipal* aPrincipal) : mPrincipal(aPrincipal) {}
+  operator nsIPrincipal*() const { return mPrincipal.get(); }
+
+private:
+  // Unimplemented
+  Principal& operator=(Principal&);
+  nsCOMPtr<nsIPrincipal> mPrincipal;
+};
+
+template <>
+struct ParamTraits<Principal>
+{
+  typedef Principal paramType;
+  static void Write(Message* aMsg, const paramType& aParam);
+  static bool Read(const Message* aMsg, void** aIter, paramType* aResult);
+};
+
+} // namespace IPC
+
+#endif // mozilla_dom_permission_message_utils_h__
+