Store the time at which a RemoteControlClient changes it playback
state, and send that time to the IRemoteControlDisplay.
This change will enable displays to implement strategies such as
timeouts (e.g. to not display transport controls for clients which have
been paused or stopped for a certain amount of time).
Change-Id: I902882500565743d455d56f6000efaf612cbe0a9
68622396b6