Added boilerplate code for being able to test the upcoming
AEC functionality.

BUG=webrtc:5201

Review URL: https://codereview.webrtc.org/1700703005

Cr-Original-Commit-Position: refs/heads/master@{#11647}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: a332e2d3afd67547eb7063394b7168490bc8287e
8 files changed