Another little-known trick with google's CDN URLs is this:

Just leave out the "http:" or "https:"
ie: http://fonts.googleapis.com/blahblah would become: //fonts.googleapis.com/blahblah

It'll automatically pick up whichever protocol is in use on the current page.

(caveat: I've not tested this extensively, but have seen it used a few times and it worked fantastically)