Make WebRTC.Video.AdaptChangesPerMinute.Quality stats only based on changes during a call.
Discard initial quality adapt changes due to bitrate (MaximumFrameSizeForBitrate).
Makes stats only based on changes determined by the quality scaler.
Bug: none
Change-Id: I461b65e65634565ade87b1336cf5206aa14926ff
Reviewed-on: https://webrtc-review.googlesource.com/37660
Reviewed-by: Rasmus Brandt <brandtr@webrtc.org>
Commit-Queue: Åsa Persson <asapersson@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#21585}