Over-The-Air Installs - stay connected to users across their devices

With Google Play services v3.0, now you can drive automatic Android downloads from your website sign-ins. After signing in with Google on the web, users have the option to send your Android app to their device instantly, without them ever leaving your website. Direct installs from the Google Play Store are limited to free apps that exceed a quality threshold.

Link: https://developers.google.com/+/features/play-installs