The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/c36154affd237e23ffce17ed8c99e9aafa535300

commit c36154affd237e23ffce17ed8c99e9aafa535300
Author: Eliot Courtney <edcourtney@google.com>
Date: Thu Sep 21 06:56:54 2017

Remove unmaintained message center flag and related code.

Bug:  767288 
Change-Id: Ib46feedebe019d6ed8ff03fa3100dc45e55843d7
Reviewed-on: https://chromium-review.googlesource.com/676824
Reviewed-by: Yoshiki Iguchi <yoshiki@chromium.org>
Commit-Queue: Eliot Courtney <edcourtney@chromium.org>
Cr-Commit-Position: refs/heads/master@{#503374}
[modify] https://crrev.com/c36154affd237e23ffce17ed8c99e9aafa535300/chrome/browser/about_flags.cc
[modify] https://crrev.com/c36154affd237e23ffce17ed8c99e9aafa535300/chrome/browser/flag_descriptions.cc
[modify] https://crrev.com/c36154affd237e23ffce17ed8c99e9aafa535300/chrome/browser/flag_descriptions.h
[modify] https://crrev.com/c36154affd237e23ffce17ed8c99e9aafa535300/ui/message_center/message_center_switches.h
[modify] https://crrev.com/c36154affd237e23ffce17ed8c99e9aafa535300/ui/message_center/public/cpp/message_center_switches.cc
[modify] https://crrev.com/c36154affd237e23ffce17ed8c99e9aafa535300/ui/message_center/public/cpp/message_center_switches.h
[modify] https://crrev.com/c36154affd237e23ffce17ed8c99e9aafa535300/ui/message_center/views/message_list_view.cc