Remove third_party from DEPS and modify autoroller script to check chromium third_party directly into webrtc repo. Change-Id: Ib0b77fc414116babc193b2289a5e9c3256daf566 No-Presubmit: True Bug: webrtc:8366 Reviewed-on: https://webrtc-review.googlesource.com/73801 Reviewed-by: Karl Wiberg <kwiberg@webrtc.org> Reviewed-by: Patrik Höglund <phoglund@google.com> Reviewed-by: Patrik Höglund <phoglund@webrtc.org> Cr-Commit-Position: refs/heads/master@{#23204}