Change #159711 adds the option to filter out small packets on the input to the delay-based BWE. This change adds similar functionality to BitrateEstimator by reducing the weight of small observations. Bug: webrtc:10932 Change-Id: I0a673a067f7ef86769cabd30443e60e9de70053c Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/160009 Commit-Queue: Christoffer Rodbro <crodbro@webrtc.org> Reviewed-by: Björn Terelius <terelius@webrtc.org> Cr-Commit-Position: refs/heads/master@{#29865}