Dark mode secondary UI spec/refinements

This change:
- Mostly implements UX's secondary UI spec
- Switches topchrome to use the same colors as incognito, though
this may be temporary
- Replaces some temp colors

Bug: 912375, 850098

Change-Id: I447c3062455330b01c0e7381d3a9eabd2709a970
Reviewed-on: https://chromium-review.googlesource.com/c/1378408
Commit-Queue: Leonard Grey <lgrey@chromium.org>
Reviewed-by: Peter Kasting <pkasting@chromium.org>
Reviewed-by: Michael Wasserman <msw@chromium.org>
Reviewed-by: Elly Fong-Jones <ellyjones@chromium.org>
Cr-Commit-Position: refs/heads/master@{#618375}
7 files changed