The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/ec5a9b6210b486a6e945b61418f280679f6ba32a

commit ec5a9b6210b486a6e945b61418f280679f6ba32a
Author: James Cook <jamescook@chromium.org>
Date: Thu Oct 04 18:43:49 2018

chromeos: Show SingleProcessMash warning button in shelf

There are no visible differences in SingleProcessMash mode, so add an
indicator to the shelf so developers know they are in a special mode.

This is similar to what we do for feature Mash.

Bug:  890400 
Test: run --enable-features=SingleProcessMash, see button
Change-Id: Ic44dda5b077892a289de8ad1902707b91f3f247a
Reviewed-on: https://chromium-review.googlesource.com/c/1252632
Commit-Queue: James Cook <jamescook@chromium.org>
Reviewed-by: Mitsuru Oshima <oshima@chromium.org>
Cr-Commit-Position: refs/heads/master@{#596777}
[modify] https://crrev.com/ec5a9b6210b486a6e945b61418f280679f6ba32a/ash/extended_desktop_unittest.cc
[modify] https://crrev.com/ec5a9b6210b486a6e945b61418f280679f6ba32a/ash/shelf/shelf_layout_manager_unittest.cc
[modify] https://crrev.com/ec5a9b6210b486a6e945b61418f280679f6ba32a/ash/shelf/shelf_view_unittest.cc
[modify] https://crrev.com/ec5a9b6210b486a6e945b61418f280679f6ba32a/ash/system/flag_warning/flag_warning_tray.cc
[modify] https://crrev.com/ec5a9b6210b486a6e945b61418f280679f6ba32a/ash/system/status_area_widget.cc