[Dark] Update dark color palette

+ Update dark hairline color to grey 700
+ Update dark elevation colors

Bug: 959284, 958916
Change-Id: Iffbb9a7ddbcb2ef7844ce18d02e9e287a5c34de0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1623305
Reviewed-by: Theresa <twellington@chromium.org>
Commit-Queue: Becky Zhou <huayinz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#661980}
2 files changed