Fix issue #20494208: Go out of device idle when headset button is pressed

Rework how we record active transitions in battery stats to be
more general, and add an API that others can call in to
DeviceIdleController to request that we go out of idle mode.
use this for VOICE_SEARCH_HANDS_FREE.

Change-Id: Ie58de60e63036a4142881283835961fbcceec892