Audio event logging
New class AudioEventLogger to store a configurable number of the
last audio events. It hosts a circular buffer of lightweight
event objects, an abstract class whose implementations are
event-specific, and does the heavier string manipulations
at the time of the dump, not during normal operation.
Add logging for:
- phone state (a.k.a. audio mode) changes
- wired device connections
- playback activity monitor
- force use
Test: adb shell dumpsys audio
Bug:
64470715
Change-Id: I8dbd936e2ffec39134f1a8837191c74f5cb9fc56