This CL corrects the way that the estimated filter delay is used in
AEC3. In particular
-It uses the filter delay to choose the correct render block in AecState
-It changes the code to reflect that the filter delay is always computed
-It removes part of the code that formerly relied on the filter delay
being an Optional.
Bug: webrtc:8671
Change-Id: I58135a5c174b404707e19a41c3617c09831e871d
Reviewed-on: https://webrtc-review.googlesource.com/35221
Reviewed-by: Gustaf Ullberg <gustaf@webrtc.org>
Commit-Queue: Per Åhgren <peah@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#21557}