title: Control another app's audio playback
body: <p>I'm trying to write app to control audio playback from another app. </p>
  
  <p>For example: i listen music in google play and my app can intercept control of this audio stream. I dont dont know will it be widget or foreground service with notitication, but i cant find information how to check if music playing in system and how to get access to control it.</p>
  
  <p>I found <code>MediaSession</code>, <code>MediaBrowserService</code> and so on. But it's implementation about inside one app with creating service to play music background and creating client part as i UI part and gain access to Auto, Google Assistant and so on. But i want to write just client part, take information about currently playing music and write some widget to control it by myself</p>
  
  <p>What can i google to find out the solution?</p>