Add a runtime setting that notifies play-out audio device changes.
The payload is a pair indicating a device id and its maximum play-out
volume.
kPlayoutVolumeChange is now forwarded not only to capture, but also
render (required by render_pre_processor).
Bug: webrtc:10608
Change-Id: I8997c207422c1dcd1d53775397d6290939ef3db8
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/159002
Commit-Queue: Alessio Bazzica <alessiob@webrtc.org>
Reviewed-by: Per Åhgren <peah@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#29725}