With the current AEC algorithm, the divergence of the echo cancelling linear filter is a strong signal of non-transparency. During double talk, it can result in a ducking artifacts.
In this CL, a metric that tells the fraction of filter divergence is added. This can measure the severity of non-transparency.
BUG=
Review URL: https://codereview.webrtc.org/1739993003
Cr-Commit-Position: refs/heads/master@{#12276}
e10fc3fb2d