Google Play Services 7.5 update shows a glimpse of the functionality that's heading towards Android apps

The announcement gives us a taste of what we can expect from Android apps in the very near future - we're talking pre-Android M, as everything you'll be reading about is readily available to Android users. Here's the gist of it!

Smart Lock for Passwords

This feature retrieves saved credentials from the Chrome Password Manager as part of the login process, and saves new credentials for later use on other Android devices and instances of Chrome. This will let users stay logged in as they move between devices, so they will no longer have to log out or create multiple accounts. Smart Lock supports both traditional passwords and Identity Provider credentials.

Instance ID

Google has added Instance ID, which lets developers retrieve an unique identifier for every app instance. This lets apps authenticate and authorize actions even if they don't have registration and accounts. By looking at the Instance ID token, devs can determine which app instance is sending authorization requests.

App Invites Beta

App Invites is a new piece of functionality for both Android and iOS devices which lets developers invite their contacts to install their preview apps through a standardized user interface. Invites can be sent via SMS and email.

source: Android Developers Blog