The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/cd157cc064b027602e61ae6bf51c30c6d94e0875

commit cd157cc064b027602e61ae6bf51c30c6d94e0875
Author: kylechar <kylechar@chromium.org>
Date: Wed May 30 17:30:02 2018

viz: Add child HWND for software compositing.

Add child HWND in the GPU process when using OOP-D software compositing.
OOP-D moves the software compositor from the browser process into the
GPU process. There are undesirable artifacts during resize where pixels
from the existing window content are repeated in the unpainted region.
GPU compositing uses a child HWND to prevent resize artifacts already.

The child HWND is on the same thread as the display compositor. This is
different than GPU compositing where the child HWND has a dedicated
thread. The dedicated thread was added as a potential fix for a GPU
process hang but doesn't look to have worked from
https://crbug.com/596190#c138. If necessary we can do something similar
for software compositing

Bug:  835906 
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: I7195aaea18bca56084cd2ac3c6d1079668e92f13
Reviewed-on: https://chromium-review.googlesource.com/1025954
Commit-Queue: kylechar <kylechar@chromium.org>
Reviewed-by: Sunny Sachanandani <sunnyps@chromium.org>
Reviewed-by: danakj <danakj@chromium.org>
Cr-Commit-Position: refs/heads/master@{#562890}
[modify] https://crrev.com/cd157cc064b027602e61ae6bf51c30c6d94e0875/components/viz/service/display_embedder/gpu_display_provider.cc
[modify] https://crrev.com/cd157cc064b027602e61ae6bf51c30c6d94e0875/components/viz/service/display_embedder/software_output_device_win.cc
[modify] https://crrev.com/cd157cc064b027602e61ae6bf51c30c6d94e0875/components/viz/service/display_embedder/software_output_device_win.h
[modify] https://crrev.com/cd157cc064b027602e61ae6bf51c30c6d94e0875/components/viz/service/gl/gpu_service_impl.cc
[modify] https://crrev.com/cd157cc064b027602e61ae6bf51c30c6d94e0875/components/viz/service/gl/gpu_service_impl.h
[modify] https://crrev.com/cd157cc064b027602e61ae6bf51c30c6d94e0875/components/viz/service/main/viz_main_impl.cc
[modify] https://crrev.com/cd157cc064b027602e61ae6bf51c30c6d94e0875/gpu/ipc/in_process_command_buffer.cc
[modify] https://crrev.com/cd157cc064b027602e61ae6bf51c30c6d94e0875/gpu/ipc/service/gles2_command_buffer_stub.cc
[modify] https://crrev.com/cd157cc064b027602e61ae6bf51c30c6d94e0875/gpu/ipc/service/gpu_channel_manager_delegate.h
[modify] https://crrev.com/cd157cc064b027602e61ae6bf51c30c6d94e0875/gpu/ipc/service/gpu_channel_test_common.cc