chrome will run adschorme.js auto ,this make my $.fn.extend undefined

chrome will run adschorme.js auto ,this make my $.fn.extend undefined

<script type="text/javascript" src="/resource/base/JQUERY-1.9.1.JS"></script>
<script>

      $.fn.extend($.fn,{aa:function(){alert("aa");}})

      $().ready(function(){
            $("#reg_form").aa();                        //success ,$.fn.aa return right function
            $("#reg_form :input").focus(function(){
                  $("#reg_form").aa();                  //error,chrome sign : object[object object] has no mothod 'aa',because chrome run adschorme.js auto ,when breakpoint set to adschorme,$.fn.aa return undefined
            });
      });
</script>
<body>
<div id="reg_form">
<input type="text" />
</div>
</body>