Add new builder with enable_webrtc=false.

We want Chromium to build with enable_webrtc=false. I will initially
add a build bot in chromium.webrtc.

Bug: chromium:811678
Change-Id: If3f23a70f0102f5b65bb46e5e91eee3c0b1bbeb2
Reviewed-on: https://chromium-review.googlesource.com/960125
Commit-Queue: Patrik Höglund <phoglund@chromium.org>
Reviewed-by: John Budorick <jbudorick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#544013}
3 files changed