This is closely related to  http://crbug.com/686848 . The plan as of the last time I sat down with rjkroege@ was to make DisplayConfigurationController an interface and have a Mojo implementation for mash. So likely cash would continue to use DisplayManager directly until a full Mojo implementation exists. I guess once mushrome launches the non-Mojo implementation would be obsolete and could be removed.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/494c6cbdea529cc6aa1e4e344bdc732d61d91d3a

commit 494c6cbdea529cc6aa1e4e344bdc732d61d91d3a
Author: sky <sky@chromium.org>
Date: Mon Mar 27 20:57:48 2017

Gets chrome --mus some what working

This makes chrome work in --mus mode. It comes up and displays stuff,
but I have no doubt a bunch of stuff doesn't work.

BUG= 704985 , 705592 , 705595 , 705591 , 678949 
TEST=none
R=erg@chromium.org

Review-Url: https://codereview.chromium.org/2777223002
Cr-Commit-Position: refs/heads/master@{#459875}

[modify] https://crrev.com/494c6cbdea529cc6aa1e4e344bdc732d61d91d3a/ash/aura/wm_shell_aura.cc
[modify] https://crrev.com/494c6cbdea529cc6aa1e4e344bdc732d61d91d3a/ash/aura/wm_shell_aura.h
[modify] https://crrev.com/494c6cbdea529cc6aa1e4e344bdc732d61d91d3a/ash/common/wm_shell.h
[modify] https://crrev.com/494c6cbdea529cc6aa1e4e344bdc732d61d91d3a/ash/mus/bridge/wm_shell_mus.cc
[modify] https://crrev.com/494c6cbdea529cc6aa1e4e344bdc732d61d91d3a/ash/mus/bridge/wm_shell_mus.h
[modify] https://crrev.com/494c6cbdea529cc6aa1e4e344bdc732d61d91d3a/ash/mus/test/wm_test_helper.cc
[modify] https://crrev.com/494c6cbdea529cc6aa1e4e344bdc732d61d91d3a/ash/mus/window_manager.cc
[modify] https://crrev.com/494c6cbdea529cc6aa1e4e344bdc732d61d91d3a/ash/mus/window_manager.h
[modify] https://crrev.com/494c6cbdea529cc6aa1e4e344bdc732d61d91d3a/ash/mus/window_manager_application.cc
[modify] https://crrev.com/494c6cbdea529cc6aa1e4e344bdc732d61d91d3a/ash/public/cpp/BUILD.gn
[add] https://crrev.com/494c6cbdea529cc6aa1e4e344bdc732d61d91d3a/ash/public/cpp/config.h
[modify] https://crrev.com/494c6cbdea529cc6aa1e4e344bdc732d61d91d3a/ash/shell.cc
[modify] https://crrev.com/494c6cbdea529cc6aa1e4e344bdc732d61d91d3a/ash/shell.h
[modify] https://crrev.com/494c6cbdea529cc6aa1e4e344bdc732d61d91d3a/ash/test/ash_test_helper.cc
[modify] https://crrev.com/494c6cbdea529cc6aa1e4e344bdc732d61d91d3a/chrome/browser/chromeos/BUILD.gn
[add] https://crrev.com/494c6cbdea529cc6aa1e4e344bdc732d61d91d3a/chrome/browser/chromeos/ash_config.cc
[add] https://crrev.com/494c6cbdea529cc6aa1e4e344bdc732d61d91d3a/chrome/browser/chromeos/ash_config.h
[modify] https://crrev.com/494c6cbdea529cc6aa1e4e344bdc732d61d91d3a/chrome/browser/chromeos/preferences.cc
[modify] https://crrev.com/494c6cbdea529cc6aa1e4e344bdc732d61d91d3a/chrome/browser/ui/BUILD.gn
[modify] https://crrev.com/494c6cbdea529cc6aa1e4e344bdc732d61d91d3a/chrome/browser/ui/ash/ash_init.cc
[modify] https://crrev.com/494c6cbdea529cc6aa1e4e344bdc732d61d91d3a/chrome/browser/ui/ash/ash_init.h
[modify] https://crrev.com/494c6cbdea529cc6aa1e4e344bdc732d61d91d3a/chrome/browser/ui/ash/ash_util.cc
[modify] https://crrev.com/494c6cbdea529cc6aa1e4e344bdc732d61d91d3a/chrome/browser/ui/ash/ash_util.h
[modify] https://crrev.com/494c6cbdea529cc6aa1e4e344bdc732d61d91d3a/chrome/browser/ui/ash/chrome_shell_delegate.cc
[modify] https://crrev.com/494c6cbdea529cc6aa1e4e344bdc732d61d91d3a/chrome/browser/ui/views/ash/chrome_browser_main_extra_parts_ash.cc
[modify] https://crrev.com/494c6cbdea529cc6aa1e4e344bdc732d61d91d3a/chrome/browser/ui/views/ash/chrome_browser_main_extra_parts_ash.h
[modify] https://crrev.com/494c6cbdea529cc6aa1e4e344bdc732d61d91d3a/chrome/browser/ui/views/chrome_browser_main_extra_parts_views.cc
[modify] https://crrev.com/494c6cbdea529cc6aa1e4e344bdc732d61d91d3a/chrome/browser/ui/views/chrome_browser_main_extra_parts_views.h
[modify] https://crrev.com/494c6cbdea529cc6aa1e4e344bdc732d61d91d3a/chrome/browser/ui/views/frame/native_browser_frame_factory_chromeos.cc
[modify] https://crrev.com/494c6cbdea529cc6aa1e4e344bdc732d61d91d3a/ui/aura/mus/window_manager_delegate.h
[modify] https://crrev.com/494c6cbdea529cc6aa1e4e344bdc732d61d91d3a/ui/aura/mus/window_tree_client.cc
[modify] https://crrev.com/494c6cbdea529cc6aa1e4e344bdc732d61d91d3a/ui/aura/mus/window_tree_client.h

I believe this is fixed now.