Protect _transportPtr, which can be accessed by different threads in the case of external transport. This change avoid the potential use-after-free, e.g. the case in the reported bug.

BUG=2508
RISK=P1
TEST=try bots
R=henrika@webrtc.org, xians@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/2425004

git-svn-id: http://webrtc.googlecode.com/svn/trunk/webrtc@5000 4adac7df-926f-26a2-2b94-8c16560cd09d
1 file changed