Detect if WebGL is on Facebook canvas

Hi

Im currently facing an issue where I am using the Facebook plugin v.7.1.0 for Unity. Im distributing through WebGL, but my app needs to be running both on Facebook, but also outside Facebook. When using FB.Init I get a successful callback, which is what I used to use for testing whether on Facebook canvas or not when deploying for WebPlayer.

So my question is, how do I detect whether the WebGL player is on the facebook canvas or not?