change parameter to public as suggested in Platform & Plugins forum:

http://forum.piwik.org/read.php?9,117763

core/Tracker/Action.php

@@ -70,9 +70,11 @@ static public function factory(Request $request)
     }
 
     /**
+     * Public so that events listener can access it
+     *
      * @var Request
      */
-    protected $request;
+    public $request;
 
     private $idLinkVisitAction;
     private $actionIdsCached = array();