title: Quick return action bar with android lollipop toolbar
body: <p>I am using the new toolbar of AppCompat-v21. What I want to do is to hide the action bar when the user starts scrolling downwards and show the action bar again when the user scroll upwards. Its just like the google play app. I also have a tab layout below the toolbar like the google play app. That needs to stay there.</p>
  
  <p>I have tried using codes from google IO app. But it makes the toolbar disappear and the main content does not move up when the toolbar disappears. There remains a void space where to toolbar was before. Maybe its because that implementation is only for list and grid views.</p>
  
  <p>Any idea how to do that?</p>