Send the now playing list changed events after media updates

Bug: 63585280
Test: Test with BWM carkit and see in snoop logs that now playing list changes
      happen after addressed player changes

CL updated with follow-up changes from the following CLs:
  72225a3a
  093a2e4d

Change-Id: I79766077d8531dab5716902c4a25363dc0197442
Merged-In: I79766077d8531dab5716902c4a25363dc0197442
(cherry picked from commit be8be56f)