commit 012aa375b177897c2aa28d9744ad36b2b95ca30f
author Henrik Boström <hbos@webrtc.org> Mon Apr 27 15:40:55 2020
committer Commit Bot <commit-bot@chromium.org> Tue Apr 28 09:00:15 2020
tree abc74e5611117427816e677b18e5e382cd1f8d34
parent 9abc6bd8aa85b23079221956463379d80d5426c2

Asynchronous QualityScaler: Callback-based CheckQpTask.

This CL breaks up the CheckQp() operation into several steps managed
by the inner helper class CheckQpTask, making responding to high or
low QP an asynchronous operation. Why? Reconfiguring the stream in
response to QP overuse will in the future be handled on a separate
task queue. See Call-Level Adaptation Processing for more details:
https://docs.google.com/document/d/1ZyC26yOCknrrcYa839ZWLxD6o6Gig5A3lVTh4E41074/edit?usp=sharing

Instead of "bool AdaptDown()" when high QP is reported,
synchronously returning true or false depending on the result of
adaptation, this CL introduces
  void QualityScalerQpUsageHandlerInterface::OnReportQpUsageHigh(
      rtc::scoped_refptr<QualityScalerQpUsageHandlerCallback>);
Where
  QualityScalerQpUsageHandlerCallback::OnQpUsageHandled(
      bool clear_qp_samples);
Instructs the QualityScaler whether to clear samples before
checking QP the next time or to increase the frequency of checking
(corresponding to AdaptDown's return value prior to this CL).

QualityScaler no longer using AdaptationObserverInterface, this class
is renamed and moved to overuse_frame_detector.h.

The dependency between CheckQpTasks is made explicit with
CheckQpTask::Result and variables like observed_enough_frames_,
adapt_called_ and adapt_failed_ are moved there and given more
descriptive names.

Bug: webrtc:11521
Change-Id: I7faf795aeee5ded18ce75eb1617f88226e337228
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/173760
Reviewed-by: Evan Shrubsole <eshr@google.com>
Reviewed-by: Ilya Nikolaevskiy <ilnik@webrtc.org>
Commit-Queue: Henrik Boström <hbos@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#31140}