I'm curious about this "d3d11 zero copy" issue, is there any doc about this ?

there's not much documentation.

d3d11_video_decoder.cc is the decoder, though d3d11_video_decoder_impl.cc does most of the work.

the implementation for zero copy just shares the texture from the d3d11 VideoDecoder with chrome's compositor directly.  right now, that requires that they're sharing the same angle context / running on the same thread.

in the future, we'll likely make it multithreaded.  i tried prototyping that, but i couldn't get it to work properly.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/1590e9c6af87e5d77449c53698988a5817f1518d

commit 1590e9c6af87e5d77449c53698988a5817f1518d
Author: Frank Liberato <liberato@chromium.org>
Date: Fri Jun 22 23:29:52 2018

Add D3D11 feature level check to D3D11VideoDecoder.

Bug:  844494 
Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel;luci.chromium.try:linux_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;luci.chromium.try:win_optional_gpu_tests_rel
Change-Id: Ia5cac58367ca7e532c92f16a4418397c38230216
Reviewed-on: https://chromium-review.googlesource.com/1110437
Commit-Queue: Frank Liberato <liberato@chromium.org>
Reviewed-by: Dan Sanders <sandersd@chromium.org>
Cr-Commit-Position: refs/heads/master@{#569837}
[modify] https://crrev.com/1590e9c6af87e5d77449c53698988a5817f1518d/media/gpu/BUILD.gn
[modify] https://crrev.com/1590e9c6af87e5d77449c53698988a5817f1518d/media/gpu/windows/d3d11_cdm_proxy.cc
[modify] https://crrev.com/1590e9c6af87e5d77449c53698988a5817f1518d/media/gpu/windows/d3d11_cdm_proxy.h
[modify] https://crrev.com/1590e9c6af87e5d77449c53698988a5817f1518d/media/gpu/windows/d3d11_cdm_proxy_unittest.cc
[add] https://crrev.com/1590e9c6af87e5d77449c53698988a5817f1518d/media/gpu/windows/d3d11_create_device_cb.h
[modify] https://crrev.com/1590e9c6af87e5d77449c53698988a5817f1518d/media/gpu/windows/d3d11_decryptor.h
[modify] https://crrev.com/1590e9c6af87e5d77449c53698988a5817f1518d/media/gpu/windows/d3d11_decryptor_unittest.cc
[modify] https://crrev.com/1590e9c6af87e5d77449c53698988a5817f1518d/media/gpu/windows/d3d11_mocks.cc
[modify] https://crrev.com/1590e9c6af87e5d77449c53698988a5817f1518d/media/gpu/windows/d3d11_mocks.h
[modify] https://crrev.com/1590e9c6af87e5d77449c53698988a5817f1518d/media/gpu/windows/d3d11_video_decoder.cc
[modify] https://crrev.com/1590e9c6af87e5d77449c53698988a5817f1518d/media/gpu/windows/d3d11_video_decoder.h
[modify] https://crrev.com/1590e9c6af87e5d77449c53698988a5817f1518d/media/gpu/windows/d3d11_video_decoder_unittest.cc