backer@ has talked about implementing passthrough. Is that a separate bug? Or is this the bug for passthrough?

We have a bug for OOP-R with passthrough (issue 829435). There may be additional work to make SkiaRenderer + SkDDL work. 

I have a short CL up to make it work with CPU raster. I've tested it with my OOP-R for passthrough prototype and that works as well.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/c649646549d03be00f4ba32f0f71eb14d51dac68

commit c649646549d03be00f4ba32f0f71eb14d51dac68
Author: Jonathan Backer <backer@chromium.org>
Date: Thu Nov 22 21:52:47 2018

Make SkRender,SkDDL work with passthrough decoder

Works with these flags on Linux build with DCHECKs enabled:

 --use-gl=angle --use-angle=gl --use-cmd-decoder=passthrough --enable-features="VizDisplayCompositor,UseSkiaRenderer,UseSkiaDeferredDisplayList"

Bug:  892272 
Change-Id: I48c2caec780a6243b58e3ed1b2c60240f7a3b213
Reviewed-on: https://chromium-review.googlesource.com/c/1348589
Reviewed-by: weiliangc <weiliangc@chromium.org>
Reviewed-by: Peng Huang <penghuang@chromium.org>
Commit-Queue: Jonathan Backer <backer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#610491}
[modify] https://crrev.com/c649646549d03be00f4ba32f0f71eb14d51dac68/components/viz/service/display/resource_metadata.h
[modify] https://crrev.com/c649646549d03be00f4ba32f0f71eb14d51dac68/components/viz/service/display_embedder/skia_output_surface_impl.cc
[modify] https://crrev.com/c649646549d03be00f4ba32f0f71eb14d51dac68/components/viz/service/display_embedder/skia_output_surface_impl_on_gpu.cc
[modify] https://crrev.com/c649646549d03be00f4ba32f0f71eb14d51dac68/gpu/command_buffer/service/skia_utils.cc
[modify] https://crrev.com/c649646549d03be00f4ba32f0f71eb14d51dac68/gpu/command_buffer/service/skia_utils.h
[modify] https://crrev.com/c649646549d03be00f4ba32f0f71eb14d51dac68/gpu/ipc/service/gpu_channel_manager.cc