title: getRunningTasks doesn't work in Android L
body: <p>In Android L, Google has disabled getRunningTasks. Now it can only return own apps task and the home launcher.  I can no longer get other apps tasks. 
  Our app needs that method to determine current top app. 
  Any one has another method to do this?</p>
  
  <p>I have searched in Google, no more topics about this except this:
  <a href="https://code.google.com/p/android-developer-preview/issues/detail?id=29">https://code.google.com/p/android-developer-preview/issues/detail?id=29</a></p>