alessiob 54ad3df1d2 I added two factory classes to address an important comment I got in another CL from kjellander@webrtc.org.
This CL also includes the implementation of the echo noise generator.
I added comments in the diff to help the reviewers.

BUG=webrtc:7218
NOTRY=True

Review-Url: https://codereview.webrtc.org/2715233003
Cr-Commit-Position: refs/heads/master@{#17507}
2017-04-03 15:12:44 +00:00
..

Name: WebRTC
URL: http://www.webrtc.org
Version: 90
License: BSD
License File: LICENSE

Description:
WebRTC provides real time voice and video processing
functionality to enable the implementation of 
PeerConnection/MediaStream.

Third party code used in this project is described 
in the file LICENSE_THIRD_PARTY.