title: singleTask Activity called from Service doesn't trigger onNewIntent
body: <p>My understanding was that a singleTask activity, if it exists already, is not going to be created again, but its onNewIntent is going to be called.</p>
  
  <p>In fact, that's what happens when I start an Intent from another Activity, but not from a service.</p>
  
  <p>Furthermore, I noticed that this doesn't happen if I declare my Activity to be singleInstance (i.e in this case, even from a service onNewIntent does get called) but it also involves back stack complications that I don't want.</p>
  
  <p>My undesrtanding was that onNewIntent would always be called, if I have an instance of the singleTask Activity running, and it does work that way from an Activity but not a service.</p>
  
  <p>Why is that, and what should I do to keep my back stack intact and just bring my existing activity to the top from my service?</p>
  
  <p>Note: I do have the FLAG_ACTIVITY_NEW_TASK when I call my singleTask Activity.</p>
  
  <p>Thanks!</p>