title: Broadcast receiver invoke when another applications a particular activity is opened
body: <p>I wand a <code>Broadcast receiver</code> invoke when another applications a particular <code>activity</code> is opened in android. For example When <code>Navigation</code> page in <code>Map</code> application that installed in <code>android</code> phone, When opened and showing the Navigation, I want to show a <code>Toast</code> that display "Currently showing Navigation". So how can I achieve that?</p>