Revert r6390 "Adds end to end DataChannel tests." Flaky on linux_memcheck

This reverts commit c3272a942f04f9dd0db3f6bf0d201bcf47c3fa08.

TBR=wu@webrtc.org
BUG=2626

Review URL: https://webrtc-codereview.appspot.com/13689004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@6420 4adac7df-926f-26a2-2b94-8c16560cd09d
json.h include different header files depending on WEBRTC_CHROMIUM_BUILD being defined or not. Since json.h/cc is not even used in chromium it is the wrong flag to use. Instead add WEBRTC_EXTERNAL define. Also added OWNERS for base which is a copy of system_wrappers owners as the two folders are being merged.

BUG=3379
R=niklas.enbom@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/15779004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@6421 4adac7df-926f-26a2-2b94-8c16560cd09d