Extend perf tests to perform rampup on single stream.

R=kjellander@webrtc.org, stefan@webrtc.org
BUG=3065

Review URL: https://webrtc-codereview.appspot.com/10049004

git-svn-id: http://webrtc.googlecode.com/svn/trunk/webrtc@5733 4adac7df-926f-26a2-2b94-8c16560cd09d
1 file changed