This change is part of the implementation of the Insertable Streams Web API: https://github.com/alvestrand/webrtc-media-streams/blob/master/explainer.md Design doc for WebRTC library changes: http://doc/1eiLkjNUkRy2FssCPLUp6eH08BZuXXoHfbbBP1ZN7EVk Bug: webrtc:11380 Change-Id: I491ecefc60d184b75128799274c7d7efcf907d2a Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/169128 Reviewed-by: Magnus Flodman <mflodman@webrtc.org> Reviewed-by: Danil Chapovalov <danilchap@webrtc.org> Commit-Queue: Marina Ciocea <marinaciocea@webrtc.org> Cr-Commit-Position: refs/heads/master@{#30666}