Use real video duration instead of test duration to calculate harmonic frame rate in DefaultVideoQualityAnalyzer. Bug: webrtc:11445 Change-Id: Ia5f96b2f87178419ec6ebe2ff5dbcb5a0c03c824 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/171104 Reviewed-by: Ilya Nikolaevskiy <ilnik@webrtc.org> Commit-Queue: Artem Titov <titovartem@webrtc.org> Cr-Commit-Position: refs/heads/master@{#30854}