Fix Chrome Push Notifications to work with FireBase
Google Could Messaging (GCM) is depricated starting May 28, 2015 and since GCM was powering Chrome Desktop Notifications it may not work as expected. If you have problems with it you may need to change the Project Number with the one from FireBase Console here:
While API key is located in the same place as before as explained in the video here: https://www.youtube.com/watch?v=yHzz3Ui2yS4&t=87s
Note: Keep in mind that after you do this change your existing subscribers will not receive notifications until they re-register.