Get Started With Push Notifications On Android

[Costas]

http://code.tutsplus.com/tutorials/how-to-get-started-with-push-notifications-on-android--cms-25870

Reference - https://developers.google.com/drive/v3/web/push#registering-your-domain

First you must whitelist your domain (from where, you will send the pushes)
https://www.google.com/webmasters/tools/home?hl=en