Add common colors in night- and some initial clean up on themes

+ Add night- variant for some semantic color references
+ Change themes to inherit DayNight theme
+ Unify some themes to share the base set of style and color attributes
+ Add naming convention for themes

NOPRESUBMIT=true
(Bypass AlertDialog.Builder error since I'm not adding new ones)

Bug: 925564
Change-Id: Ice5066812027ae791522ca0cdc5a21110b597b11
Reviewed-on: https://chromium-review.googlesource.com/c/1437201
Commit-Queue: Becky Zhou <huayinz@chromium.org>
Reviewed-by: John Budorick <jbudorick@chromium.org>
Reviewed-by: Theresa <twellington@chromium.org>
Cr-Commit-Position: refs/heads/master@{#630466}
119 files changed