The same as https://webrtc-review.googlesource.com/c/src/+/331340, but for interleaved messages. This avoids inserting into maps where possible, and also fixes a bug when the payload was accidentally copied unintentionally - crbug.com/365594101. Bug: chromium:365594101 Change-Id: Iaeaa97b0cf3a26ada9afc61f2545760b7ab4c731 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/363960 Reviewed-by: Florent Castelli <orphis@webrtc.org> Commit-Queue: Victor Boivie <boivie@webrtc.org> Cr-Commit-Position: refs/heads/main@{#43099}