chrome.runtime.sendMessage({

check: "UserAgent"

}, function(n) {

if (n.userAgent != "") {

var t = document.createElement("script");

t.type = "text/javascript";

t.text = "navigator.__defineGetter__('userAgent', function () { return '" + n.userAgent + "'; });";

document.getElementsByTagName("head")[0].appendChild(t);

}

});