Changes how window is updated when display changes in mash

ash/test/ash_test_helper.cc

 // Copyright 2013 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.
 
 #include "ash/test/ash_test_helper.h"
 
 #include "ash/accelerators/accelerator_controller_delegate_aura.h"
 #include "ash/aura/wm_shell_aura.h"
 #include "ash/common/test/test_session_state_delegate.h"
 #include "ash/common/test/test_system_tray_delegate.h"
@@ skipping 350 matching lines @@
       ManagedDisplayInfo::CreateFromSpec(display_spec);
   gfx::Rect bounds = display_info.bounds_in_native();
   bounds.set_x(*next_x);
   *next_x += bounds.size().width();
   display::Display updated_display =
       root_window_controller->GetWindow()->GetDisplayNearestWindow();
   gfx::Insets work_area_insets = updated_display.GetWorkAreaInsets();
   updated_display.set_bounds(bounds);
   updated_display.UpdateWorkAreaFromInsets(work_area_insets);
   updated_display.set_device_scale_factor(display_info.device_scale_factor());
-  root_window_controller->GetWindow()->SetBounds(gfx::Rect(bounds.size()));
-  ScreenMus* screen = window_manager_app_->window_manager()->screen_.get();
-  const bool is_primary =
-      screen->display_list().FindDisplayById(updated_display.id()) ==
-      screen->display_list().GetPrimaryDisplayIterator();
-  screen->display_list().UpdateDisplay(
-      updated_display, is_primary ? display::DisplayList::Type::PRIMARY
-                                  : display::DisplayList::Type::NOT_PRIMARY);
+  window_manager_app_->window_manager()->OnWmDisplayModified(updated_display);
 }
 
 std::vector<RootWindowController*> AshTestHelper::GetRootsOrderedByDisplayId() {
   std::set<RootWindowController*> roots =
       window_manager_app_->window_manager()->GetRootWindowControllers();
   std::vector<RootWindowController*> ordered_roots;
   ordered_roots.insert(ordered_roots.begin(), roots.begin(), roots.end());
   std::sort(ordered_roots.begin(), ordered_roots.end(), &CompareByDisplayId);
   return ordered_roots;
 }
 
 }  // namespace test
 }  // namespace ash