diff -r 000000000000 -r 6474c204b198 toolkit/mozapps/extensions/test/browser/cancelCompatCheck.sjs
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolkit/mozapps/extensions/test/browser/cancelCompatCheck.sjs	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,44 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Delay before responding to an HTTP call attempting to read
+// an addon update RDF file
+
+function handleRequest(req, resp) {
+  resp.processAsync();
+  resp.setHeader("Cache-Control", "no-cache, no-store", false);
+  resp.setHeader("Content-Type", "text/xml;charset=utf-8", false);
+
+  let file = null;
+  getObjectState("SERVER_ROOT", function(serverRoot)
+  {
+    file = serverRoot.getFile("browser/toolkit/mozapps/extensions/test/browser/browser_bug557956.rdf");
+  });
+  dump("*** cancelCompatCheck.sjs: " + file.path + "\n");
+  let fstream = Components.classes["@mozilla.org/network/file-input-stream;1"].
+                  createInstance(Components.interfaces.nsIFileInputStream);
+  fstream.init(file, -1, 0, 0);
+  let cstream = null;
+  cstream = Components.classes["@mozilla.org/intl/converter-input-stream;1"].
+          createInstance(Components.interfaces.nsIConverterInputStream);
+  cstream.init(fstream, "UTF-8", 0, 0);
+
+  // The delay can be passed on the query string
+  let delay = req.queryString + 0;
+
+  timer = Components.classes["@mozilla.org/timer;1"].
+          createInstance(Components.interfaces.nsITimer);
+  timer.init(function sendFile() {
+    dump("cancelCompatCheck: starting to send file\n");
+    let (str = {}) {
+      let read = 0;
+      do {
+        // read as much as we can and put it in str.value
+        read = cstream.readString(0xffffffff, str);
+        resp.write(str.value);
+      } while (read != 0);
+    }
+    cstream.close();
+    resp.finish();
+  }, delay, Components.interfaces.nsITimer.TYPE_ONE_SHOT);
+}