Remove window/host accessors from WED; IWYU for WTH

ash/display/screen_position_controller_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/screen_position_controller.h"
 
 #include "ash/display/display_manager.h"
 #include "ash/screen_util.h"
 #include "ash/shell.h"
 #include "ash/test/ash_test_base.h"
 #include "ash/test/shell_test_api.h"
 #include "ui/aura/env.h"
 #include "ui/aura/test/test_window_delegate.h"
-#include "ui/aura/window_event_dispatcher.h"
+#include "ui/aura/window_tree_host.h"
 #include "ui/base/layout.h"
 #include "ui/gfx/screen.h"
 
 #if defined(OS_WIN)
 // TODO(scottmg): RootWindow doesn't get resized immediately on Windows
 // Ash. http://crbug.com/247916.
 #define MAYBE_ConvertHostPointToScreen DISABLED_ConvertHostPointToScreen
 #define MAYBE_ConvertHostPointToScreenHiDPI DISABLED_ConvertHostPointToScreenHiDPI
 #define MAYBE_ConvertHostPointToScreenRotate DISABLED_ConvertHostPointToScreenRotate
 #define MAYBE_ConvertHostPointToScreenUIScale DISABLED_ConvertHostPointToScreenUIScale
@@ skipping 246 matching lines @@
   EXPECT_EQ("210,70", ConvertHostPointToScreen(60, 70));
   // The point is out of the host windows.
   EXPECT_EQ("210,-50", ConvertHostPointToScreen(60, -50));
   // The point is on the 2nd host. Point on 1nd host (60, 60)
   // 1/2 * 1.5 = (45,45)
   EXPECT_EQ("45,45", ConvertHostPointToScreen(60, -340));
 }
 
 }  // namespace test
 }  // namespace ash