title: Collapsing Bottom Bar (like Google Music) in Android
body: <p>I know how to implement a collapsing toolbar with the android design library.
  But how do i implement a collapsing bottom bar like the one that is implemented in <a href="http://i.giphy.com/l41lGf55cvMO0HeEM.gif" rel="nofollow">googles play music app</a>?</p>