P2PTransportChannl will be renamed to IceTransport and this class will be the base class of IceTransport. By doing this, the Dtls related methods can be separated from the IceTransport. For more detail, https://docs.google.com/document/d/1g9RA0s4RV7hFAcWiAM2b6H5ZohAVpBqcYienEDj6IcY/edit BUG=none Review-Url: https://codereview.webrtc.org/2577183004 Cr-Commit-Position: refs/heads/master@{#15690}