This allows use of webrtc field trials and opens up the possibility to try the different code paths when running the unit tests by wiring them up to a --force_fieldtrials. Tested: running a test target that links with the above with a flag --force_fieldtrials=invalid leads the test to crash. BUG=crbug/367114 R=mflodman@webrtc.org, phoglund@webrtc.org Review URL: https://webrtc-codereview.appspot.com/19439004 git-svn-id: http://webrtc.googlecode.com/svn/trunk@6181 4adac7df-926f-26a2-2b94-8c16560cd09d