Update to API for a client to notify what type of information
changed (e.g. playstate, metadata) to optimize small updates
without the remote control display having to do expensive
queries such as album art.
When the remote control display retrieves the flags about
what information changed, the flag gets cleared.
Change-Id: I7d3d8d3eecd1da44695d84905ed9e7b70fe38b86
7b6198cacc