Mash browser frame: fix incognito text color (used in popup windows)

Remove incognito member variable from CustomFrameHeader and make the
text color part of the AppearanceProvider (in Mash, this relies on
window properties).

Also move some functionality from CustomFrameViewAsh to HeaderView so
that when BrowserNonClientFrameViewAsh uses HeaderView, it will benefit
from it as well.

Bug: 837705
Change-Id: I7cb4aa654b37a6a9f8f73864c745f15245a15fc3
Reviewed-on: https://chromium-review.googlesource.com/1117883
Commit-Queue: Evan Stade <estade@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Reviewed-by: Mitsuru Oshima <oshima@chromium.org>
Reviewed-by: Michael Wasserman <msw@chromium.org>
Cr-Commit-Position: refs/heads/master@{#575662}
13 files changed