Good question. It's actually just an illusion. My page simply instructs your computer to connect to Google's servers, and then "wraps" the responses from Google at the page level into frames. I literally cannot see anything at all that you send to Google or receive from Google. In fact, this entire app is 100% client-side, so it never communicates with my server except to download the initial code (ok, fine, and favicon).

There was an old trick years ago where mischievous webmasters would "wrap" a file:// URL in their web page to make it look like their page had access to all the files on your computer. Again, it's just a wrapper. No data is transmitted to or from the server about what's in the wrapper.