Move DisplayManager and DisplayChangeObserverX11 from aura to ash.

ash/ash.gyp

Index: ash/ash.gyp
diff --git a/ash/ash.gyp b/ash/ash.gyp
index ac60ac8315903db1e029a1ba2b152f3a00b7b7f7..ce847a8b9120cd41edbf28f15f6f02256ab3ac63 100644
--- a/ash/ash.gyp
+++ b/ash/ash.gyp
@@ -75,14 +75,16 @@
         'desktop_background/desktop_background_widget_controller.cc',
         'desktop_background/desktop_background_widget_controller.h',
         'desktop_background/user_wallpaper_delegate.h',
+        'display/display_change_observer_x11.cc',
+        'display/display_change_observer_x11.h',
         'display/display_controller.cc',
         'display/display_controller.h',
         'display/display_error_dialog.cc',
         'display/display_error_dialog.h',
+        'display/display_manager.cc',
+        'display/display_manager.h',
         'display/mouse_cursor_event_filter.cc',
         'display/mouse_cursor_event_filter.h',
-        'display/multi_display_manager.cc',
-        'display/multi_display_manager.h',
         'display/output_configurator_animation.cc',
         'display/output_configurator_animation.h',
         'display/screen_position_controller.cc',
@@ -460,15 +462,14 @@
       'sources': [
         'test/ash_test_base.cc',
         'test/ash_test_base.h',
-        'test/ash_unittests.cc',
         'test/capture_tracking_view.cc',
         'test/capture_tracking_view.h',
         'test/cursor_manager_test_api.cc',
         'test/cursor_manager_test_api.h',
         'test/launcher_view_test_api.cc',
         'test/launcher_view_test_api.h',
-        'test/multi_display_manager_test_api.cc',
-        'test/multi_display_manager_test_api.h',
+        'test/display_manager_test_api.cc',
+        'test/display_manager_test_api.h',
         'test/test_activation_delegate.cc',
         'test/test_activation_delegate.h',
         'test/test_launcher_delegate.cc',
@@ -523,7 +524,7 @@
         'dip_unittest.cc',
         'display/display_controller_unittest.cc',
         'display/mouse_cursor_event_filter_unittest.cc',
-        'display/multi_display_manager_unittest.cc',
+        'display/display_manager_unittest.cc',
         'display/screen_position_controller_unittest.cc',
         'drag_drop/drag_drop_controller_unittest.cc',
         'drag_drop/drag_drop_tracker_unittest.cc',
@@ -554,6 +555,7 @@
         'shell/window_watcher_unittest.cc',
         'system/tray/system_tray_unittest.cc',
         'system/web_notification/web_notification_tray_unittest.cc',
+        'test/ash_unittests.cc',
         'tooltips/tooltip_controller_unittest.cc',
         'wm/activation_controller_unittest.cc',
         'wm/base_layout_manager_unittest.cc',