Default-enable WebRTC-H264WithOpenH264FFmpeg.

Enables WebRTC H.264 by default in preparation for M52.

BUG=chromium:468365, chromium:500605
R=avi@chromium.org

Review-Url: https://codereview.chromium.org/1965513002
Cr-Commit-Position: refs/heads/master@{#392519}
1 file changed