Move DisplayChangeObserver + tests from ash to ui.

ash/BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//testing/test.gni")
 import("//ui/base/ui_features.gni")
 
 # Historical note: Ash shipped on Windows for a couple years to support
@@ skipping 598 matching lines @@
     "common/wm_window_user_data.h",
     "debug.cc",
     "debug.h",
     "default_wallpaper_delegate.cc",
     "default_wallpaper_delegate.h",
     "display/cursor_window_controller.cc",
     "display/cursor_window_controller.h",
     "display/display_animator.h",
     "display/display_animator_chromeos.cc",
     "display/display_animator_chromeos.h",
-    "display/display_change_observer_chromeos.cc",
-    "display/display_change_observer_chromeos.h",
     "display/display_color_manager_chromeos.cc",
     "display/display_color_manager_chromeos.h",
     "display/display_configuration_controller.cc",
     "display/display_configuration_controller.h",
     "display/display_error_observer_chromeos.cc",
     "display/display_error_observer_chromeos.h",
     "display/display_pref_util.h",
     "display/display_util.cc",
     "display/display_util.h",
     "display/event_transformation_handler.cc",
@@ skipping 630 matching lines @@
     "common/system/tray/tri_view_unittest.cc",
     "common/system/user/tray_user_unittest.cc",
 
     # TODO: convert to use AshTest http://crbug.com/654517.
     "common/wallpaper/wallpaper_controller_unittest.cc",
 
     # TODO: convert to use AshTest http://crbug.com/654524.
     "common/wm/overview/cleanup_animation_observer_unittest.cc",
     "dip_unittest.cc",
     "display/cursor_window_controller_unittest.cc",
-    "display/display_change_observer_chromeos_unittest.cc",
     "display/display_color_manager_chromeos_unittest.cc",
     "display/display_error_observer_chromeos_unittest.cc",
     "display/display_manager_unittest.cc",
     "display/display_util_unittest.cc",
     "display/extended_mouse_warp_controller_unittest.cc",
     "display/json_converter_unittest.cc",
     "display/mirror_window_controller_unittest.cc",
     "display/mouse_cursor_event_filter_unittest.cc",
     "display/projecting_observer_chromeos_unittest.cc",
     "display/resolution_notification_controller_unittest.cc",
@@ skipping 229 matching lines @@
   if (is_win) {
     configs -= [ "//build/config/win:console" ]
     configs += [ "//build/config/win:windowed" ]
     deps += [ "//sandbox" ]
   }
 
   if (is_chromeos) {
     deps += [ "//device/bluetooth" ]
   }
 }