GitLab

Previously, light-mode tooltips were light-on-dark, and dark-mode were
dark-on-light.  This reverses that, since opposite-scheme tooltips stick out
oddly and look buggy.  For example, on CrOS, hovering a tab gave a dark-on-light
"tooltip" (preview), but hovering the new tab button was light-on-dark.

Since translucent tooltips will now stand out less, this adds a border, just as
non-translucent tooltips have.  This also makes non-translucent tooltips more
closely resemble translucent ones by using GetResultingPaintColor() instead of
simply clamping opacity.

Bug: 1024091
Change-Id: Ie6cda816b285423446d8d8f119288683b913d3dc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1931756
Auto-Submit: Peter Kasting <pkasting@chromium.org>
Commit-Queue: Scott Violet <sky@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#718723}