Poorly designed applications like this one? https://accounts.google.com/Logout
<iframe src="https://accounts.google.com/Logout" width="0" height="0" ></iframe>"X-Frame-Options" is used to defend against click-jacking attacks, not to defend against CSRF.
<form id="form" method="post" action="https://accounts.google.com/Logout"></form>
<script>$('#form').submit()</script>
The correct way of dealing with this issue is to rely on CSRF tokens.What's your point? Google must be incapable of poor design? Everything a big company does is good?
Also, full disclosure: I work for Google.