Merge change 2520 into donut

* changes:
  Cause the icon drawables to animate automatically by calling setVisible false and then true on the drawables. For an AnimationDrawable, this will trigger the desired behavior of 'automatically' starting the animation, which should have been working to begin with according to the intended design of AnimationDrawable (see http://b/1878430 for my description of my correspondence with Romain). For Donut we'll just do this to work around it, but for a later release we need to decide a better story.