ash: Cleanup class/struct forward declarations

ash/test/ash_test_base.h

 // 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.
 
 #ifndef ASH_TEST_ASH_TEST_BASE_H_
 #define ASH_TEST_ASH_TEST_BASE_H_
 
 #include <stdint.h>
 
 #include <memory>
 #include <string>
 
 #include "ash/common/material_design/material_design_controller.h"
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "base/message_loop/message_loop.h"
 #include "base/threading/thread.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "third_party/skia/include/core/SkColor.h"
 #include "ui/display/display.h"
 #include "ui/wm/public/window_types.h"
 
 #if defined(OS_WIN)
 #include "ui/base/win/scoped_ole_initializer.h"
 #endif
 
 namespace aura {
-class RootWindow;
 class Window;
 class WindowDelegate;
 }  // namespace aura
 
 namespace display {
 class DisplayManager;
 
 namespace test {
 class DisplayManagerTestApi;
 }  // namespace test
@@ skipping 170 matching lines @@
   ~NoSessionAshTestBase() override {}
 
  private:
   DISALLOW_COPY_AND_ASSIGN(NoSessionAshTestBase);
 };
 
 }  // namespace test
 }  // namespace ash
 
 #endif  // ASH_TEST_ASH_TEST_BASE_H_