Framework: hold back to kill app (1/2)
AudioService: Don't adjust volume when vol-downing to vibrate or silent

Pressing vol-down to vibrate or silent would (previously) still adjust the
stream volume, setting the last audible volume to 0, which is not allowed
for voice-capable devices.  Thus, the last audible volume would reset to
default on reboot if on vibrate/silent or the lowest volume setting.

By not adjusting volume when vol-downing to vibrate or silent on
voice-capable devices, the last audible volume is always preserved across
reboot.
Framework Track Control: Switch from broadcast to audio service

Ordered broadcast is unreliable.
Switch to using the Audio Service's dispatchMediaKeyWithWakeLockToAudioService
as it sends the event to the correct receiver.