First step to only expose the relevant RNN VAD API to AGC2. Bug: webrtc:7494 Change-Id: I7f11f6eebded124c30cabd64963c8e3ccc35e58f Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/185124 Commit-Queue: Alessio Bazzica <alessiob@webrtc.org> Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org> Cr-Commit-Position: refs/heads/master@{#32185}