Added code for MediaStreamAudioTrackProcessing Finch Experiment enabling

Added code for MediaStreamAudioTrackProcessing Finch Experiment enabling.

NOTRY=true

BUG=351240, 264611
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=256271

[no longer working on chromium, 2014-03-11 09:44:14]

Tommi, this patch adds a flag to turn on the MediaStreamAudioTrackProcessing
when it is in finch experiment, please take a look.

Thanks,
SX

[no longer working on chromium, 2014-03-11 09:46:49]

Alexei, FYI, this is a chromium CL which enables the audio processing for the
media stream audio track. I will soon make a critique Cl to enable the feature
in Canary and Dev.

Thanks,
SX

[tommi (sloooow) - chröme, 2014-03-11 10:12:02]

lgtm

[Alexei Svitkine (slow), 2014-03-11 14:10:56]

lgtm

[no longer working on chromium, 2014-03-11 14:11:15]

The CQ bit was checked by xians@chromium.org

[commit-bot: I haz the power, 2014-03-11 14:11:17]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/xians@chromium.org/194723002/1

[no longer working on chromium, 2014-03-11 15:27:35]

The CQ bit was unchecked by xians@chromium.org

[commit-bot: I haz the power, 2014-03-11 15:30:43]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-03-11 15:30:44]

Retried try job too often on win_rel for step(s) unit_tests
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=win_rel&nu...

[no longer working on chromium, 2014-03-11 17:18:45]

The CQ bit was checked by xians@chromium.org

[commit-bot: I haz the power, 2014-03-11 17:23:00]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/xians@chromium.org/194723002/1

[commit-bot: I haz the power, 2014-03-11 17:37:42]

Change committed as 256271