diff -r 000000000000 -r 6474c204b198 dom/xslt/base/txErrorObserver.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dom/xslt/base/txErrorObserver.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,41 @@
+/* -*- Mode: C++; tab-width: 4; 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 MITRE_ERROROBSERVER_H
+#define MITRE_ERROROBSERVER_H
+
+#include "txCore.h"
+
+/**
+ * A simple interface for observing errors
+**/
+class ErrorObserver {
+
+public:
+
+    /**
+     * Default Destructor for ErrorObserver
+    **/
+    virtual ~ErrorObserver() {};
+
+    /**
+     *  Notifies this Error observer of a new error aRes
+    **/
+    virtual void receiveError(const nsAString& errorMessage, nsresult aRes) = 0;
+
+    /**
+     *  Notifies this Error observer of a new error, with default
+     *  error code NS_ERROR_FAILURE
+    **/
+    void receiveError(const nsAString& errorMessage)
+    {
+        receiveError(errorMessage, NS_ERROR_FAILURE);
+    }
+
+        
+
+}; //-- ErrorObserver
+
+#endif