Microsoft is currently testing some new features on its Xbox beta app on the Google Play Store. The biggest new feature of the beta app is the addition of party chat through your Android mobile device.
This allows players to stay connected on any platform: Xbox One, Windows 10, and eventually Android and iOS. If you're out enjoying yourself, you can still be chatting to your friends who are at home playing Minecraft or PlayerUnknown's Battlegrounds. There's no word as to when this feature will be moved over to the live app though.
The Xbox beta app isn't a new thing. Microsoft has kept it around for some time now, to provide "an early peek at new capabilities". It's been around long enough that the app's store URL still lists "Smartglass" in the title, a branding Microsoft has long since dropped.