Add place holder to move gfx::Display/Screen to ui/display

ui/display/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/ui.gni")
 import("//testing/test.gni")
 
 component("display") {
   sources = [
     "chromeos/apply_content_protection_task.cc",
@@ skipping 14 matching lines @@
     "chromeos/x11/display_mode_x11.cc",
     "chromeos/x11/display_mode_x11.h",
     "chromeos/x11/display_snapshot_x11.cc",
     "chromeos/x11/display_snapshot_x11.h",
     "chromeos/x11/display_util_x11.cc",
     "chromeos/x11/display_util_x11.h",
     "chromeos/x11/native_display_delegate_x11.cc",
     "chromeos/x11/native_display_delegate_x11.h",
     "chromeos/x11/native_display_event_dispatcher_x11.cc",
     "chromeos/x11/native_display_event_dispatcher_x11.h",
+    "display.h",
     "display_export.h",
+    "display_observer.h",
     "display_switches.cc",
     "display_switches.h",
     "manager/display_layout.cc",
     "manager/display_layout.h",
     "manager/display_layout_builder.cc",
     "manager/display_layout_builder.h",
+    "screen.h",
     "win/display_info.cc",
     "win/display_info.h",
     "win/dpi.cc",
     "win/dpi.h",
     "win/screen_win.cc",
     "win/screen_win.h",
     "win/screen_win_display.cc",
     "win/screen_win_display.h",
   ]
 
@@ skipping 120 matching lines @@
     ]
   }
 
   if (is_chromeos && use_ozone) {
     sources -= [
       "chromeos/x11/display_util_x11_unittest.cc",
       "chromeos/x11/native_display_event_dispatcher_x11_unittest.cc",
     ]
   }
 }