Utilizing the AEC3 config struct for constants.

This CL replaces inline constants with config struct
constants.

BUG=webrtc:5298

Review-Url: https://codereview.webrtc.org/3003733002
Cr-Original-Commit-Position: refs/heads/master@{#19507}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 8cee56f2546c329d193d9478e29894cf9f6ad2ff
20 files changed