diff -r 000000000000 -r 6474c204b198 xpcom/ds/nsHashPropertyBag.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/xpcom/ds/nsHashPropertyBag.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,44 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* 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 nsHashPropertyBag_h___
+#define nsHashPropertyBag_h___
+
+#include "nsIVariant.h"
+#include "nsIWritablePropertyBag.h"
+#include "nsIWritablePropertyBag2.h"
+#include "nsInterfaceHashtable.h"
+
+class nsHashPropertyBag : public nsIWritablePropertyBag
+                               , public nsIWritablePropertyBag2
+{
+public:
+    nsHashPropertyBag() { }
+    virtual ~nsHashPropertyBag() {}
+
+    NS_DECL_THREADSAFE_ISUPPORTS
+
+    NS_DECL_NSIPROPERTYBAG
+
+    NS_DECL_NSIPROPERTYBAG2
+
+    NS_DECL_NSIWRITABLEPROPERTYBAG
+
+    NS_DECL_NSIWRITABLEPROPERTYBAG2
+
+protected:
+    // a hash table of string -> nsIVariant
+    nsInterfaceHashtable<nsStringHashKey, nsIVariant> mPropertyHash;
+};
+
+#undef  IMETHOD_VISIBILITY
+#define IMETHOD_VISIBILITY NS_VISIBILITY_HIDDEN
+
+// Note: NS_NewHashPropertyBag returns a HPB that
+// uses a non-thread-safe internal hash
+extern "C" nsresult
+NS_NewHashPropertyBag(nsIWritablePropertyBag* *_retval);
+
+#endif /* nsHashPropertyBag_h___ */