Sorry, I have no experience of Chrome.
Try placing this in a function
Code:
function useKey() {
var a = "" + (window.getSelection() ? document.getSelection() : document.selection.createRange().text);
if (a!=null)window.open("http://www.google.com/search?q=\"" + escape(a)+ "\"");
}
and call the function when the selected key is pressed (see code given above in Post#2).