Signed deltas can yield a more efficient encoding when the encoded sequence sometimes moves backwards. Bug: webrtc:8111 Change-Id: Ib1a50192851214ccc3f2bd7eaf88f4be97e4beb0 Reviewed-on: https://webrtc-review.googlesource.com/c/100423 Commit-Queue: Elad Alon <eladalon@webrtc.org> Reviewed-by: Björn Terelius <terelius@webrtc.org> Cr-Commit-Position: refs/heads/master@{#25324}