The audio mixer has a subcomponent called FrameCombiner, which uses an
AudioProcessing instance as a limiter. The limiter smoothly increases
the volume to avoid causing clipping.
The limiter was created in a default configuration causing the
ResidualEchoDetector submodule of AudioProcessing to be
activated. That submodule operates in the band-split domain (see
AudioProcessingImpl::ApmSubmoduleStates::RenderMultiBandSubModulesActive()).
There is a goal to remove the (expensive and unnecessary)
band-splitting from AudioMixer. This change helps accomplish that. (It
can't be done yet, because the actual limiter sub-component of APM
also operates in the band-split domain).
BUG=webrtc:6185
Review-Url: https://codereview.webrtc.org/2875623002
Cr-Commit-Position: refs/heads/master@{#18090}
0f23fa8768