Make PacketTransportInternal inherit from PacketTransportInterface.

Was just overlooked in an earlier CL.

BUG=webrtc:7013
TBR=pthatcher@webrtc.org

Review-Url: https://codereview.webrtc.org/2806463003
Cr-Original-Commit-Position: refs/heads/master@{#17579}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 225bfc0971e2986bd42af5c0a6f5c70fa07b6dd3
3 files changed