Handle dark mode for active/hover trace.

Final screencast: https://screencast.googleplex.com/cast/NjM4MzU5MjU2NDMyNjQwMHxkMjY4MmRlZC0wYg

Bug: 340509046
Test: npm run test:unit:ci
Change-Id: I6f59cf20c6e74289022130eb50b8ee18ae52c657
7 files changed