GN: Changes for vp9, opus and direct trace

Corresponding GN changes for
https://webrtc-codereview.appspot.com/34099004/

BUG=4185
R=brettw@chromium.org

Review URL: https://webrtc-codereview.appspot.com/40669004

Cr-Original-Commit-Position: refs/heads/master@{#8377}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: ce22f13f0e1864bfeddc4d17d75a3918865c7bd4
5 files changed