title: Fragment's onResume() not called when popped from backstack
body: <p>Hi I am developing android application in which I am using I am using single <code>Activity</code> and 3 fragments. So consider I have 3 fragments A B C. When I switch from A to B, I am adding <code>Fragment</code> to backstack and simillar for B to C. Now when I click back from C it shows me B and similar for B to A as well.</p>
  
  <p>But thing is that when I come from C to B or B to A, it's not calling <code>onResume()</code> or any other life cycle methods of <code>Fragment</code>. </p>
  
  <p>What I want to do actually for every <code>Fragment</code> I have different title in <code>ActionBar</code>. So, in my code, when I move from A to B or B to c, I am changing activity title inside fragment. But when I click on back it not changing according to that.</p>
  
  <p>What is the actual problem? Why after pop from backstack its not calling <code>onResume()</code> for my <code>Fragment</code>? How do I solve this problem? Need Help. Thank you.</p>