The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/b1028aa7a6a0d86d3f978d0275b711d047a8a1f9

commit b1028aa7a6a0d86d3f978d0275b711d047a8a1f9
Author: Maggie Chen <magchen@chromium.org>
Date: Wed Sep 26 00:31:43 2018

Do not downscale direct composition overlay layers in Windows

1. If HW overlay scaling is supported, set swap chain size to the minimum of the decoded
video buffer size and the onscreen video size.
2. If HW overlay scaling is not supported, set swap chain size to onscreen video size.

This CL removes overlay down scaling, and therefore fixes no hardware overlays due to
down scaling not working on Intel display HW.

BUG=868561

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: I251ddb4f5e24807dd7267eca38180cae241fb6f6
Reviewed-on: https://chromium-review.googlesource.com/1225295
Commit-Queue: Maggie Chen <magchen@chromium.org>
Reviewed-by: Sunny Sachanandani <sunnyps@chromium.org>
Reviewed-by: Zhenyao Mo <zmo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#594159}
[modify] https://crrev.com/b1028aa7a6a0d86d3f978d0275b711d047a8a1f9/gpu/ipc/service/direct_composition_surface_win.cc
[modify] https://crrev.com/b1028aa7a6a0d86d3f978d0275b711d047a8a1f9/gpu/ipc/service/direct_composition_surface_win.h
[modify] https://crrev.com/b1028aa7a6a0d86d3f978d0275b711d047a8a1f9/gpu/ipc/service/direct_composition_surface_win_unittest.cc

After this CL "Do not downscale direct composition overlay layers in Windows". The extra BLT inside DWM will be eliminated in the overlay downscaling case. This should improve power in video playback for both overlay and underlay.