title: on popBackStack() which method invoked in previous fragment
body: <p>I have Fragment A.
  On clicking some button, i add Fragment B above Fragment A.</p>
  
  <pre><code>    FragmentB fragmentB= new FragmentB ();
      FragmentManager fragmentManager = getFragmentManager();
      FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
      fragmentTransaction.add(R.id.content_home, fragmentB, "fragmentB");
      fragmentTransaction.hide(FragmentA.this);
      fragmentTransaction.addToBackStack(FragmentA.class.getName());
      fragmentTransaction.commit();
  </code></pre>
  
  <p>I perform some action in Fragment B. After finishing my work i popBackStack() current fragment. </p>
  
  <pre><code>  FragmentManager   fragmentManager = getFragmentManager();
    fragmentManager.popBackStack();
  </code></pre>
  
  <p>Now i Fragment A. Since i used "ADD fragment" all my values are kept in edittext. </p>
  
  <p>I want to know, which method is invoked when i come back to Fragment A, 
  is it onResume()..?
  I have to put log in onResume, seems like it not going to onResume! </p>