Fix NPE when referencing child fragments

Child fragments are now added to the parent fragment's
fragment manager due to a change in framework behavior (ag/489316).

As a result we now need to use the child fragment manager to obtain
references to child fragments.

Bug: 15872707
Change-Id: I351cfbee780129448c1a748716a3c4895fca67e7
1 file changed
tree: 0d1b3fd94b9aea5c6d9b98edc489e0f5ea6fc0fe
  1. InCallUI/