The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/acebc493efd25b364a4d726c9850092f25d21dc9

commit acebc493efd25b364a4d726c9850092f25d21dc9
Author: Leonard Grey <lgrey@chromium.org>
Date: Tue Jan 22 16:03:13 2019

Preserve input color alpha in BlendTowardMaxContrast

As implemented, BlendTowardMaxContrast will blend the given color with white or GoogleGrey900, even in the degenerate case where it's given a transparent color. This has unintended results, especially in cases where a color is transparent only under some conditions (for example, combo box borders in Dark Mode).

This change preserves the alpha of the original color, which solves the transparent input edge case and is arguably closer to caller expectations.

Bug: 922846

Change-Id: I907a38841286b146eec57b3e211e90da7b030892
Reviewed-on: https://chromium-review.googlesource.com/c/1409914
Commit-Queue: Leonard Grey <lgrey@chromium.org>
Reviewed-by: Peter Kasting <pkasting@chromium.org>
Cr-Commit-Position: refs/heads/master@{#624793}
[modify] https://crrev.com/acebc493efd25b364a4d726c9850092f25d21dc9/ui/gfx/color_utils.cc
[modify] https://crrev.com/acebc493efd25b364a4d726c9850092f25d21dc9/ui/gfx/color_utils.h
[modify] https://crrev.com/acebc493efd25b364a4d726c9850092f25d21dc9/ui/gfx/color_utils_unittest.cc

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/3c6936f2ecf4957aaf3f47d457c2e2557024d501

commit 3c6936f2ecf4957aaf3f47d457c2e2557024d501
Author: Leonard Grey <lgrey@chromium.org>
Date: Tue Jan 22 20:50:35 2019

MD refresh spec catchup: disabled combo boxes

Uses the enabled color at 38% rather than the disabled button color from typography provider.

Bug: 922846

Change-Id: I0b03574b07d95c22b6dec7e3ea82c3e709666cec
Reviewed-on: https://chromium-review.googlesource.com/c/1412996
Reviewed-by: Michael Wasserman <msw@chromium.org>
Commit-Queue: Leonard Grey <lgrey@chromium.org>
Cr-Commit-Position: refs/heads/master@{#624905}
[modify] https://crrev.com/3c6936f2ecf4957aaf3f47d457c2e2557024d501/ui/views/controls/combobox/combobox.cc