chromeos: converts TopLevelWindowFactoryTest to AshTestBase

ash/display/window_tree_host_manager_unittest.cc

 // Copyright (c) 2012 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/display/window_tree_host_manager.h"
 
 #include <memory>
 
 #include "ash/display/display_util.h"
 #include "ash/screen_util.h"
@@ skipping 162 matching lines @@
   int workarea_changed_count_;
   int primary_changed_count_;
   int64_t changed_display_id_;
 
   int focus_changed_count_;
   int activation_changed_count_;
 
   DISALLOW_COPY_AND_ASSIGN(TestObserver);
 };
 
-display::Display GetPrimaryDisplay() {
-  return display::Screen::GetScreen()->GetDisplayNearestWindow(
-      Shell::GetAllRootWindows()[0]);
-}
-
 class TestHelper {
  public:
   explicit TestHelper(test::AshTestBase* delegate);
   ~TestHelper();
 
   void SetSecondaryDisplayLayoutAndOffset(
       display::DisplayPlacement::Position position,
       int offset);
 
   void SetSecondaryDisplayLayout(display::DisplayPlacement::Position position);
@@ skipping 1508 matching lines @@
       widget->GetNativeWindow()->GetRootWindow());
   event_generator.MoveMouseToCenterOf(widget->GetNativeWindow());
 
   UpdateDisplay("300x300");
   watcher.Stop();
 
   widget->CloseNow();
 }
 
 }  // namespace ash