This changes TransportControlView to be "sticky" on lockscreen. Basically, once it
appears on lockscreen, it stays there until unlocked and then locked again in paused state.
Tested basic design goals (using Music2):
- play then lock -> shows
- pause then lock -> not shown
- toggle pause to play while locked and not shown -> shows
- pause after played once while locked -> stays until we unlock and lock again while paused
- remote control play while paused & sleeping -> resume lockscreen -> shows
Also tested:
- configuration changes (orientation) to ensure widget continues to show after it once appears
- remote events while lock screen on -> keeps lockscreen on.
- remote events while sleeping -> doesn't wake.
Change-Id: I23418c5f7dfd1457c0844d2683772e8a3ed0abd1
4e6d35829e