Reland 54383003: Added an "enable-audio-processor" flag and WebRtcAudioProcessor class

Added an "enable-audio-processor" flag and WebRtcAudioProcessor class.


This CL is a break-down CL from https://codereview.chromium.org/37793005. As the first step to move WebRtc APM to Chrome, it adds a enable-audio-processor command line flag, the WebRtcAudioProcessor class and its unittest.
WebRtcAudioProcessor is not hooked up the any of the code in Chrome yet, but it will be exercised and tested by its unittest.


TBR=tommi@chromium.org
BUG=264611
TEST=content_unittest

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=237360

[commit-bot: I haz the power, 2013-11-26 15:13:40]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/xians@chromium.org/88513002/20001

[no longer working on chromium, 2013-11-26 15:15:56]

Tommi, FYI, I am relanding this with a fix on the dependency.

SX

[tommi (sloooow) - chröme, 2013-11-26 15:18:53]

rs lgtm

[commit-bot: I haz the power, 2013-11-26 18:23:11]

Change committed as 237360