Move DisplayList to display; add ScreenBase.

ash/display/extended_mouse_warp_controller.cc

Index: ash/display/extended_mouse_warp_controller.cc
diff --git a/ash/display/extended_mouse_warp_controller.cc b/ash/display/extended_mouse_warp_controller.cc
index ad59992defd9dc81b3f835ca30b3154698ecf5a3..235ac563769c364f5fb80f71f8c551106b98d6d8 100644
--- a/ash/display/extended_mouse_warp_controller.cc
+++ b/ash/display/extended_mouse_warp_controller.cc
@@ -105,7 +105,7 @@ ExtendedMouseWarpController::ExtendedMouseWarpController(
       Shell::GetInstance()->display_manager();
   int64_t drag_source_id = drag_source ? GetDisplayIdFromWindow(drag_source)
                                        : display::Display::kInvalidDisplayID;
-  display::DisplayList display_list = display_manager->active_display_list();
+  display::Displays display_list = display_manager->active_display_list();
   // Try to create a Warp region for all possible two displays combination.
   // The following code does it by poping the last element in the list
   // and then pairing with remaining displays in the list, until the list