Added hook for downloading reference videos to the video quality test. BUG=343504 R=kjellander@chromium.org Review URL: https://codereview.chromium.org/190753011 git-svn-id: http://src.chromium.org/svn/trunk/deps/third_party/webrtc/webrtc.DEPS@255949 4ff67af0-8c30-449e-8e8b-ad334ec8d88c