The sample app, called Universal Music Player, uses a number of new features from Android 5.0 Lollipop, and offers guidance to developers for getting their apps to work well and look good on multiple screen sizes, including phones, Android Wear devices, and Android Auto.
From the Android Developers Blog:
This sample, the Universal Music Player, is a bare-bones but functional reference app that supports multiple devices and form factors in a single codebase. It is compatible with Android Auto, Android Wear, and Google Cast devices. Give it a try and easily adapt your own app for wherever your users are, be that a phone, watch, TV, car, or more!
The app shows developers how to implement features such as putting playback controls and album art on the lock screen and controlling playback through Android Auto and Android Wear. You can check out code samples on Google's Samples GitHub page at the link below.
Source: Android Developers Blog, Google Samples GitHub
