diff -r 000000000000 -r 6474c204b198 netwerk/base/public/nsITraceableChannel.idl
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/netwerk/base/public/nsITraceableChannel.idl	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,34 @@
+/* -*- 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/. */
+
+#include "nsISupports.idl"
+
+interface nsIStreamListener;
+
+/**
+ * A channel implementing this interface allows one to intercept its data by
+ * inserting intermediate stream listeners.
+ */
+[scriptable, uuid(68167b0b-ef34-4d79-a09a-8045f7c5140e)]
+interface nsITraceableChannel : nsISupports
+{
+    /*
+     * Replace the channel's listener with a new one, and return the listener 
+     * the channel used to have. The new listener intercepts OnStartRequest, 
+     * OnDataAvailable and OnStopRequest calls and must pass them to 
+     * the original listener after examination. If multiple callers replace 
+     * the channel's listener, a chain of listeners is created.
+     * The caller of setNewListener has no way to control at which place 
+     * in the chain its listener is placed.
+     *
+     * Note: The caller of setNewListener must not delay passing 
+     * OnStartRequest to the original listener.
+     *
+     * Note2: A channel may restrict when the listener can be replaced.
+     * It is not recommended to allow listener replacement after OnStartRequest
+     * has been called.
+     */
+    nsIStreamListener setNewListener(in nsIStreamListener aListener);
+};