removing the webrtc need for having sources in it. BUG=webrtc:42226155 Change-Id: I40fbde9064f4fa629c7c6b0cf99f23ab1726da75 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/370820 Reviewed-by: Harald Alvestrand <hta@webrtc.org> Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org> Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org> Cr-Commit-Position: refs/heads/main@{#43540}