Move screen capturers from chromium to webrtc.

R=alexeypa@chromium.org, wez@chromium.org

Review URL: https://webrtc-codereview.appspot.com/1586005

git-svn-id: http://webrtc.googlecode.com/svn/trunk/webrtc@4175 4adac7df-926f-26a2-2b94-8c16560cd09d
38 files changed