Wei: Could you do this or find an owner for doing this? Thanks.

My understanding was that texture copy request would be handled in tab capture code path, and we only need to handle the bitmap copy request there.

Yea I think we were looking at calling to gl_renderer_copier (or maybe in the future a skia_renderer_copier) from there

FYI. I created a CL https://crrev.com/c/1370890 to use SkBitmap to support i420 format or scaled request. It could be a temporary fix for this issue.

Sorry Peng. I should have commented here. I chatted with Wei last week and created a similar CL: https://chromium-review.googlesource.com/c/chromium/src/+/1369631

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/5ad979c01ef9839318dd131541a2889f5c904c7e

commit 5ad979c01ef9839318dd131541a2889f5c904c7e
Author: Jonathan Backer <backer@chromium.org>
Date: Thu Dec 13 14:52:24 2018

CPU scaling and color transform on CopyOutputRequest

Copy from SoftwareRenderer.

This fixes some unit tests and may be performant enough to small field
trial. There are still unit tests failing
(AuraWindowVideoCaptureDeviceBrowserTest), but I will address that in a
separate CL.

GLAndSoftwareCompositing*, WebContentsVideoCaptureDeviceBrowserTest*,
DevToolsVideoConsumerTest.SetMinAndMaxFramesChangesDimensions
content_browsertests now passing.

Bug:  911796 
Change-Id: Ib933f4a6e5cebed4af3bf35c1b23cf97fe54540f
Reviewed-on: https://chromium-review.googlesource.com/c/1369631
Reviewed-by: Yuri Wiitala <miu@chromium.org>
Reviewed-by: weiliangc <weiliangc@chromium.org>
Commit-Queue: Jonathan Backer <backer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#616314}
[modify] https://crrev.com/5ad979c01ef9839318dd131541a2889f5c904c7e/components/viz/service/display/skia_output_surface.h
[modify] https://crrev.com/5ad979c01ef9839318dd131541a2889f5c904c7e/components/viz/service/display/skia_renderer.cc
[modify] https://crrev.com/5ad979c01ef9839318dd131541a2889f5c904c7e/components/viz/service/display_embedder/skia_output_surface_impl.cc
[modify] https://crrev.com/5ad979c01ef9839318dd131541a2889f5c904c7e/components/viz/service/display_embedder/skia_output_surface_impl.h
[modify] https://crrev.com/5ad979c01ef9839318dd131541a2889f5c904c7e/components/viz/service/display_embedder/skia_output_surface_impl_on_gpu.cc
[modify] https://crrev.com/5ad979c01ef9839318dd131541a2889f5c904c7e/components/viz/service/display_embedder/skia_output_surface_impl_on_gpu.h
[modify] https://crrev.com/5ad979c01ef9839318dd131541a2889f5c904c7e/content/browser/media/capture/web_contents_video_capture_device_browsertest.cc

Passes content_browsertests.