When delta encoding, use ToUnsigned() and ToSigned() on timestamp_ms, since it's a signed type. This is only relevant for delta-encoding/decoding. Bug: webrtc:8111 Change-Id: I1fabfcb2be64793c281f5bc0d38a2f8035dd0d18 Reviewed-on: https://webrtc-review.googlesource.com/c/110504 Commit-Queue: Elad Alon <eladalon@webrtc.org> Reviewed-by: Björn Terelius <terelius@webrtc.org> Cr-Commit-Position: refs/heads/master@{#25602}