From natty(ubuntu 11.04),ubuntu is to use unity instead of gnome-shell.One of the feature of unity is global menu.Till now,no 3rd party application developer was supporting it.The latest chormium daily build now supports it.
Just open the browser up and enter the following command in the URL/address bar: -
In the list that opens up scroll to the very bottom of the list and enable ‘Experimental GNOME Menu bar support’ by clicking ‘Enable’.
Edit1:apparently now google chrome also support it!!!!!!!!!