[Mac] Darken tab area in accordance with new top chrome refresh.
[Mac] Darken tab area in accordance with new top chrome refresh.

TEST=none
BUG=none
Review URL: http://codereview.chromium.org/2804034

git-svn-id: http://src.chromium.org/svn/trunk/src@51452 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: abb2846df4644a2d01f5a7e48f6f7a3334e62f73
meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser