VizProcessTransportFactory is missing some code. I'll add that when I get a chance.

Flag name has changed.

In order to make this work RootCompositorFrameSinkImpl needs to create a BackToBackBeginFrameSource right around [1] if the --disable-frame-rate-limit flag was passed in. This can be modelled after how it's done in [2].

We are trying to avoid checking flags directly in components/viz/service/ so instead of checking the flag there you should. I would add the bool member |disable_frame_rate_limit| to RootCompositorFrameSinkParams Mojo struct. That way you can set the value in HostContextFactoryPrivate::ConfigureCompositor() based on the flag and don't need to pass the flag to the GPU process at all. RootCompositorFrameSinkImpl::Create() will check the value in the struct it already gets.

[1] https://cs.chromium.org/chromium/src/components/viz/service/frame_sinks/root_compositor_frame_sink_impl.cc?l=52&rcl=84513669379cc7521a00baa2a944524ee01c7394
[2] https://cs.chromium.org/chromium/src/content/browser/compositor/gpu_process_transport_factory.cc?l=575&rcl=b2684a596d28efa70f6c017550b3d7f63ac4bf61

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/21d96a446fd3586615e3a2f291ba015518539634

commit 21d96a446fd3586615e3a2f291ba015518539634
Author: Sean Gilhuly <sgilhuly@chromium.org>
Date: Tue Sep 18 14:01:26 2018

Add check for --disable-frame-rate-limit

The flag is not respected with OOP-D, so read the flag and send it to
the GPU process.

Bug:  841801 
Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel
Change-Id: I87644f9c10a04491289f9fe89b8cbbd9584bfb2a
Reviewed-on: https://chromium-review.googlesource.com/1228497
Commit-Queue: Sean Gilhuly <sgilhuly@chromium.org>
Reviewed-by: kylechar <kylechar@chromium.org>
Reviewed-by: Antoine Labour <piman@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Cr-Commit-Position: refs/heads/master@{#592029}
[modify] https://crrev.com/21d96a446fd3586615e3a2f291ba015518539634/components/viz/service/frame_sinks/root_compositor_frame_sink_impl.cc
[modify] https://crrev.com/21d96a446fd3586615e3a2f291ba015518539634/services/viz/privileged/interfaces/compositing/frame_sink_manager.mojom
[modify] https://crrev.com/21d96a446fd3586615e3a2f291ba015518539634/ui/compositor/host/host_context_factory_private.cc