How do I listen for Firebase Cloud Messaging messages in the background in a Google Chrome Extension?

I have a Google Chrome Extension that listens for GCM messages in a background script via chrome.gcm.onMessage.addListener. Our provider is planning to upgrade their infrastructure to use the latest Firebase Cloud Messaging which is no longer compatible with GCM. We’ve confirmed the gcm addListener API no longer receives messages after upgrading to FCM in the dev environment.

I’ve found migration guides for Android, iOS, and progressive web apps but none specifically for background scripts in Chrome extensions.

Some resources I’ve found:

Unrecognized manifest key ‘gcm_sender_id’ ,Chrome extension linked to fcm

am trying to link a chrome extension to firebase cloud messaging, but am getting
Unrecognized manifest key ‘gcm_sender_id’ error when i load the extension
image of the error,
here is my manifest file:

   {

  "manifest_version": 2,
  "name": "iQU",
  "description": "iQU",
  "version": "1.0",
  "browser_action": {
    "default_icon": "icon.png",
    "default_popup": "index.html"
  },
  "permissions": [],
  "content_security_policy": "script-src 'self' 'unsafe-eval' https://cdn.firebase.com https://*.firebaseio.com https://*.firebaseio.com; object-src 'self'; ",
  "web_accessible_resources": [
    "assets/css/*",
    "assets/js/*",
    "assets/fonts/*"
  ],
  "gcm_sender_id": "103953800507"
}

any help please?

Send and receive messages from firebase database through chrome extension

I followed this setup to authenticate my extension with firebase.
https://github.com/firebase/quickstart-js/tree/master/auth/chromextension

I want to push data and receive messages from the firebase db. I registered on the gcm client app. Not sure how to proceed next.

Best way to send push notifications from the server to a chrome extension?

I’m making a chrome extension for a classified ads website. With the chrome extension users will be able to get latest lists from their watched categories/search query.

I am already working on a websocket server to send notifications to users, but this way I have to always have a socket connection open to every user.

My second approach was to use Firebase, but this will run the notification only when a user clicks the icon (as I’ve read), and I would rather have this done from my server

__

Are there any other possible solutions to send notifications to a chrome extension without the user clicking on the icon?