commit 453953c9eb3f599ff8936522b7fc0124d46b84e1
author Henrik Boström <hbos@webrtc.org> Sat Mar 14 09:53:57 2020
committer Commit Bot <commit-bot@chromium.org> Sat Mar 14 11:29:03 2020
tree 0c5066c07104969553ee6ba5633928d463263696
parent 630917c39806de202caa509166d116af2fc5484b

[Adaptation] Refactor AdaptationTarget. Peek next restrictions.

This CL introduces the Adaptation class used by VideoStreamRestrictor.
This refactors the AdaptationTarget, AdaptationTargetOrReason,
CannotAdaptReason and AdaptationAction.

What is publicly exposed is simply a Status code. If it's kValid then
we can adapt, otherwise the status code describes why we can't adapt
(just like CannotAdaptReason prior to this CL). This means
AdaptationTargetOrReason is no longer needed. Target+reason are merged.

The other classes are renamed and moved and put in the private
namespace of Adaptation: Only the VideoStreamAdapter (now a friend
class of Adaptation) and its inner class VideoSourceRestrictor needs to
know how to execute the adaptation.

Publicly, you can now tell the effects of the adaptation without
applying it with PeekNextRestrictions() - both current and next steps
are described in terms of VideoSourceRestrictions. The rest are hidden.

This would make it possible, in the future, for a Resource to accept or
reject a proposed Adaptation by examining the resulting frame rate and
resolution described by the resulting restrictions. E.g. even if we are
not overusing bandwidth at the moment, the BW resource can prevent us
from applying a restriction that would exceed the BW limit before we
apply it.

This CL also moves input to a SetInput() method, and Increase/Decrease
methods of VideoSourceRestrictor are made private in favor of
ApplyAdaptationSteps().

Bug: webrtc:11393
Change-Id: Ie5e2181836ab3713b8021c1a152694ca745aeb0d
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/170111
Commit-Queue: Henrik Boström <hbos@webrtc.org>
Reviewed-by: Ilya Nikolaevskiy <ilnik@webrtc.org>
Reviewed-by: Evan Shrubsole <eshr@google.com>
Cr-Commit-Position: refs/heads/master@{#30794}