Sorry for the delayed response. This one slipped through the cracks.
What I would recommend is that you setup the Gluu Server to accept Google credentials.
You still want to dynamically enroll this person in your IDP (i.e. your Gluu Server).
Maybe take a look at this article about [Google Social Login](http://www.gluu.org/docs/articles/social-login-google/)
Also, if you can wait until tomorrow, we're going to ship 2.3.4 with the Google script installed by default.