Add a WebRTC peer connection high bitrate browser test

This CL adds a WebRTC browser tests that sets up a peer connection
between two tabs and sends video with a high target bitrate. The target
is set as 80 Mbps. To accomodate for this, call is hooked up to a fake
codec that does not really do work and can produce these rates from any
input. What we expect from this test is to track send_rate/receive_rate
stats, which are expected to be below 80 Mbps, and look for regressions
or improvements in perf bots.

Note that this CL depends on WebRTC Cl below to land first:
https://webrtc-review.googlesource.com/c/src/+/97185

Bug: 879723
Change-Id: I1b4b62db4b040d284efc1e7aac7fc6b43517a08c
Reviewed-on: https://chromium-review.googlesource.com/c/1198531
Commit-Queue: Emircan Uysaler <emircan@chromium.org>
Reviewed-by: Avi Drissman <avi@chromium.org>
Reviewed-by: Emircan Uysaler <emircan@chromium.org>
Reviewed-by: Henrik Boström <hbos@chromium.org>
Cr-Commit-Position: refs/heads/master@{#629448}
9 files changed