Google displays a popup that asks if you want to set your home page as google.com. It's quite normal, when I say OK it sets it as google.com. After that however, I don't get the popup anymore. As far as I know, nobody should be able to retrieve the value of my homepage because it's a private info. But somehow Google is tracking it. I get the popup back when I set my homepage as a different site. I deleted the cookies but even then it is only displayed when I set homepage as another site.
I tested this behavior on IE8 & IE9. The popup never shows up in Firefox and Chrome.
Internet Explorer makes it possible to ask it whether a given URL is the home page, it's detailed on this MSDN page. That links to this example page demonstrating the API.
The code Google uses can be viewed here:
google.promos.mgmhp.isGoogleHomepage = function (a) {
var b = !1;
try {
b = window.external.isGoogleHomePage()
} catch (d) {
if (h(a)) return !0;
var c = google.promos.gpd(a, "mgmhp_hp_url");
c && g.push(c);
for (c = 0; c < g.length; c++) {
var k = g[c];
if (b = b || a.isHomePage(k)) return !0
}
}
return b
};
They are using the proprietary isHomePage method to check if google.com is your homepage. More info here.
The following css code is the culprit.
behavior: url(#default#homePage) url(#default#userData);
this is why I don't really like IE. The behavior url(#default#userData) tells the browser to store this as session information on the client side or browser memory.
More information here: http://msdn.microsoft.com/en-us/library/ms533015(v=vs.85).aspx
