title: Back to main activity from notification-created activity
body: <p>I'm trying to implement the behaviour described <a href="http://developer.android.com/design/patterns/navigation.html#into-your-app" rel="noreferrer">here</a>, where a notification (or whatever) starts an "internal" activity in your app, and then when the user pressed back it goes to my "home" activity. </p>
  
  <p>The Android docs say</p>
  
  <blockquote>
    <p>In the case of the Back button, you should make navigation more
    predictable <strong><em>by inserting into the task's back stack the complete
    upward navigation path to the app's topmost screen</em></strong>. This allows users
    who've forgotten how they entered your app to navigate to the app's
    topmost screen before exiting.</p>
  </blockquote>
  
  <p>Is there a good way to actually do that? Other questions on Stackoverflow suggest starting the main activity with an intent that tells it to start the internal activity, but that seems like a huge hack, that I somewhat doubt Google would have used in Gmail, and I assume there is a decent method, given that they are advocating the behaviour.</p>
  
  <p>So is there a non-hacky way to do this?</p>