Till 9.x, the headers were under the resources in the Developer Tools, but now I can\'t find it anywhere.
My favorite way in Chrome is clicking on a bookmarklet:
javascript:(function(){function read(url){var r=new XMLHttpRequest();r.open('HEAD',url,false);r.send(null);return r.getAllResponseHeaders();}alert(read(window.location))})();
Put this code in your developer console pad.
Source: http://www.danielmiessler.com/blog/a-bookmarklet-that-displays-http-headers