Google form embed into WordPress page-how to redirect after submission

I want to redirect user to a custom page on (ie. /thank-you) after he hits submit button within a google form that I embedded on my wordpress website

I found the answer to a similar question here but it looks like google forms were updated since this as I want to embed the form and it looks like this:

<iframe src="http://ift.tt/1LtH6vS" width="760" height="500" frameborder="0" marginheight="0" marginwidth="0">Loading...</iframe>

via Chebli Mohamed