doGetDate: function() {
    var doc = gBrowser.selectedTab.linkedBrowser.contentDocument;
    if (doc.location.href != "about:blank" && doc.location.href.match(/^http:\/\//i)) {
        if (typeof this.reqUrl[doc.location.href] != "undefined") {
            document.getElementById("googledateStatusDate").value = this.reqUrl[doc.location.href];
        } else {
            var uri;
            if (this.reqCnt % 2 == 0) {
                uri = "http://www.google.co.jp/search?num=1&tbs=qdr%3Ay15&q=site%3A" + encodeURIComponent(doc.location.href);
            } else {
                uri = "http://www.google.com/search?num=1&tbs=qdr%3Ay15&q=site%3A" + encodeURIComponent(doc.location.href);
            }
            this.reqCnt++;
            var httpOj = new XMLHttpRequest();
            httpOj.open('GET', uri);
            httpOj.onreadystatechange = function() {
                if (httpOj.readyState == 4 && (httpOj.status == 200 || httpOj.status == 304)) {
                    var str = httpOj.responseText.match(/<span class="f std">.*?<\/span>/i)[0].replace(/<\/?[^>]+>/gi, "");
                    document.getElementById("googledateStatusDate").value = str;
                    googleDateHttpRequestObserver.reqUrl[doc.location.href] = str;
                }
            }
            httpOj.send(null);
        }
    }
}