Link existing Firebase and Google Cloud projects

Question

I am trying to migrate my Android app from GCM to FCM.
I use Google Cloud project for GCM and Firebase project for some Firebase features (Analytics, etc.) now.
Docs say that I need to import Google Cloud project to Firebase, but I already have Firebase project for my app. As I understand, it is needed to provide GCM and FCM tokens compatibility.

So, how to link existing Firebase and Google Cloud projects?
If it is impossible, is it possible to send messages to old tokens using new FCM endpoints and which credentials (Google Cloud or Firebase) should be used for it?

Answer 1

All Firebase project are also Google Cloud projects. You don't "link" them together - they are the same. They have exactly the same configurations and service accounts.

When you imported Firebase into your existing Google Cloud project, what you did was add Firebase APIs to it. Now you should be able to use Firebase services with your same project. It sounds like you should just start using Firebase in your project as you would normally.

The GCM and FCM backends are essentially identical, except for the endpoint that you use to send messages. So, try sending messages to the new endpoint.