WebRtcPassthroughRender has been dead since webrtcvideoengine.cc was removed, FakeExternalTransport has probably been unused for a long time. BUG=webrtc:1695 R=henrika@webrtc.org Review URL: https://codereview.webrtc.org/1343393003 . Cr-Commit-Position: refs/heads/master@{#9968}