Revert "FieldTrial implementation for webrtc." (rev 6089)

New wiring plans require it to be landed first in chrome for a cleaner roll of webrtc.

BUG=crbug/367114
R=tommi@webrtc.org
TBR=tommi@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/17479004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@6122 4adac7df-926f-26a2-2b94-8c16560cd09d