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 * Inactive tabs
  * No shape or color separate from the background.
  * Shape and color appears on hover.
  * No visible close icon until mouse hover.
  * Incognito mode colors for close icon for static/hover/pressed.

TBR=msw@chromium.org

Bug: 822061
Change-Id: I0898fcb49f1133d0922f364c0453b4436e344b35
Reviewed-on: https://chromium-review.googlesource.com/1024602
Commit-Queue: Allen Bauer <kylixrd@chromium.org>
Reviewed-by: Evan Stade <estade@chromium.org>
Reviewed-by: Peter Kasting <pkasting@chromium.org>
Cr-Commit-Position: refs/heads/master@{#554846}