Permitting double start/stopping of streams.

It doesn't make too much sense to hard enforce that the user keeps track
of which streams are started and which are not.

BUG=
R=andrew@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/6899004

git-svn-id: http://webrtc.googlecode.com/svn/trunk/webrtc@5363 4adac7df-926f-26a2-2b94-8c16560cd09d
3 files changed