Chrome Version       : v66.0.3359.139

Other browsers tested:
  Add OK or FAIL after other browsers where you have tested this issue:
       Edge: PASS

What steps will reproduce the problem?
(1) Windows 1803 (Spring update 2018) with HDR (10bit) screen.
(2) Launch chrome with hardware acceleration enabled.

What is the expected result?
White on web pages should be (at least roughly) the same color as menus.

What happens instead?
White on web pages is very dim (~50% grey), brightness unaffected by 'SDR brightness' setting of Windows.

Please provide any additional information below. Attach a screenshot if
possible.

See https://productforums.google.com/forum/#!msg/chrome/lAiOdlHS-XM/-wWDWwXTAwAJ

Benq SW271 connected over DP (UHD, 10bit @ 60Hz), 
GeForce 1060, using Windows' color settings (i.e. no overrides in the NVIDIA control panel).

When disabling hardware acceleration, the colors are correct.
Before updating Windows to 1803, colors were correct with hardware acceleration too.

For graphics-related bugs, please copy/paste the contents of the about:gpu
page at the end of this report.