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
..
2017-03-01 06:08:53 +00:00
2016-11-16 19:11:38 +00:00