To facilitate testing both the old and new AudioDeviceModule path, a setting is added to AppRTC. Enable "Use legacy audio device" to use the old path. Bug: webrtc:7452 Change-Id: I221378ac7bb0fa4e543c3fd081c7a322621621a0 Reviewed-on: https://webrtc-review.googlesource.com/64760 Reviewed-by: Henrik Andreassson <henrika@webrtc.org> Commit-Queue: Paulina Hensman <phensman@webrtc.org> Cr-Commit-Position: refs/heads/master@{#22609}