sink_filter_ds.cc: add lock to Receive procedure to Pause().

BUG=2233
TEST=AUTO Test
R=wu@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/10969004

git-svn-id: http://webrtc.googlecode.com/svn/trunk/webrtc@5827 4adac7df-926f-26a2-2b94-8c16560cd09d
1 file changed