This is a reland of f394f65b7195a5f9f71c9f0dec3bb68300590b5b
Original change's description:
> Make VideoStreamEncoder::ReconfigureEncoder always call ConfigureQualityScaler.
>
> In addition restore call to ConfigureQualityScaler in SetSource, which
> is needed if degradation preferences change mid-stream.
>
> Fixes a regressions from https://webrtc-review.googlesource.com/70740,
> The encoder's GetScalingSettings may depend on arguments to
> InitEncode, so configuring the quality scaler only at encoder creation
> time isn't enough.
>
> Bug: webrtc:8830
> Change-Id: I48f66cde219c56272f44441fdb26ec64c6002068
> Reviewed-on: https://webrtc-review.googlesource.com/72000
> Reviewed-by: Åsa Persson <asapersson@webrtc.org>
> Commit-Queue: Niels Moller <nisse@webrtc.org>
> Cr-Commit-Position: refs/heads/master@{#22993}
Bug: webrtc:8830
Change-Id: I96f0b8c27e3b58b9e9268117267abcb63ee7fe73
Reviewed-on: https://webrtc-review.googlesource.com/72320
Reviewed-by: Åsa Persson <asapersson@webrtc.org>
Commit-Queue: Niels Moller <nisse@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#23071}
2d06118623