是的。不过，直到最近才发生这种情况。

感谢@libik提供的相关文档链接：

https://firebase.google.com/docs/cloud-messaging/server#http-request

Update 5/2016：

Google宣布了FCM - Firebase云消息传递服务。随着近期宣布的Firebase在Google I / O上的扩展，我们b $ b也推出了Firebase Cloud Messaging（FCM）和Firebase
通知（FN）。作为一名开发人员，有很多更新，您
可能会利用。

更多信息： https://developers.googleblog.com/2016/05/google-cloud- messaging-and-firebase.html

文档： https://firebase.google.com/docs/cloud-messaging/#key_functions

I am investigating whether firebase and angularfire are a good fit for my upcoming project.

One of the requirements are for users to be notified when the app is closed on new private messages sent to user, ie. push notifications.

Does firebase handle this?

Yes. This was not the case until recently, though.

Thanks to @libik for providing relevant documentation link:

https://firebase.google.com/docs/cloud-messaging/server#http-request

Update 5/2016 :

on Google io 16 , Google announced FCM - Firebase cloud messaging service.

With the announced expansion of Firebase at Google I/O recently, we also introduced Firebase Cloud Messaging (FCM) and Firebase Notifications (FN). As a developer, there are lots of updates that you might be able to take advantage of.

see more at : https://developers.googleblog.com/2016/05/google-cloud-messaging-and-firebase.html

documentation : https://firebase.google.com/docs/cloud-messaging/#key_functions