a74363c998
If a port is not used by any channel and if it has no connection for 30 seconds, it will be removed. Note, as long as a port is used by a transport channel, it will be kept even if it does not have any connection. This will be beneficial to continual gathering because new connections can be created in the future when network changes. BUG= R=pthatcher@webrtc.org, zhihuang@webrtc.org Review URL: https://codereview.webrtc.org/2171183002 . Cr-Commit-Position: refs/heads/master@{#13567}