You could use JavaScript, I think something like the following should work:
Tag Archives: iframe
Widgets – iframe vs. inline
When writing a widget, should you use an iFrame or make the widget inline?
Detect iFrame embedding in Javascript
Looking at frame length breaks down generally if page A itself has frames (I know this might not be the case for this specific instance). The more reliable and meaningful test would be:
Facebook Like BTN iframe code
<iframe src=”http://www.facebook.com/plugins/like.php?href=https://www.prosoxi.com/&layout=standard&show-faces=true&width=450&action=like&colorscheme=light” allowtransparency=”true” style=”border: medium none; overflow: hidden; width: 450px; height: 26px;” scrolling=”no” frameborder=”0″></iframe>