GitLab

Add Discovery request/response and WebRtcSignalingFrame to SharingMessage
protos.

Bug: 1043149
Change-Id: I025365006d96c188308b85cc62064d48a6617f6e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2007575Reviewed-by: Alex Chau <alexchau@chromium.org>
Commit-Queue: Himanshu Jaju <himanshujaju@chromium.org>
Cr-Commit-Position: refs/heads/master@{#732938}