It looks like Google may be changing the name of their app indexing protocol from Google App Indexing to Firebase App Indexing.
Last night, I captured screen shots of Google changing the Google search developer page from saying Google App Indexing to Firebase App Indexing.
But it seems Google changed it back this morning to just App Indexing.
Yes, Firebase is a company Google acquired back in October 2014.
So it is possible Google would renamed their mobile efforts Firebase and bring App Indexing into that.
They also announced more features around this that we covered over here.