Add session state actions.

Define START_SESSION, GET_SESSION_STATUS and END_SESSION actions
for explicitly managing remote media playback sessions.

Bug: 10260186
Change-Id: Ie5ba53ba0a77112231f8e056cbf93aba236ec6f0
(cherry picked from commit b8e8322e718125cdacfac70e9605d8f9b563e6ee)
2 files changed