Add PreferredColorScheme to content::WebPreferences.

Also add the plumbing to pass it into blink.

Bug: 889087, 925935
Change-Id: I5027a1fc30b14f77423b33ac9e85ba5697a95b13
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1522246
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Commit-Queue: Rune Lillesveen <futhark@chromium.org>
Cr-Commit-Position: refs/heads/master@{#641115}
4 files changed