Is there a similar feedback service for Android GCM?
No.
If not, how to detect which Android users no longer have the app installed?
Quoting the documentation:
- The end user uninstalls the application.
- The 3rd-party server sends a message to GCM server.
- The GCM server sends the message to the device.
- The GCM client receives the message and queries Package Manager about whether there are broadcast receivers configured to receive it, which returns false.
- The GCM client informs the GCM server that the application was uninstalled.
- The GCM server marks the registration ID for deletion.
- The 3rd-party server sends a message to GCM.
- The GCM returns a NotRegistered error message to the 3rd-party server.
- The 3rd-party deletes the registration ID.
Note that it might take a while for the registration ID be completely removed from GCM. Thus it is possible that messages sent during step 7 above gets a valid message ID as response, even though the message will not be delivered to the device. Eventually, the registration ID will be removed and the server will get a NotRegistered error, without any further action being required from the 3rd-party server (this scenario happens frequently while an application is being developed and tested).