ash: Cleanup class/struct forward declarations

ash/host/ash_window_tree_host_unified.h

 // Copyright 2015 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_HOST_ASH_WINDOW_TREE_HOST_UNIFIED_H_
 #define ASH_HOST_ASH_WINDOW_TREE_HOST_UNIFIED_H_
 
 #include <vector>
 
 #include "ash/host/ash_window_tree_host_platform.h"
 #include "base/macros.h"
 #include "ui/aura/window_observer.h"
 
-namespace ui {
-class Reflector;
-}
-
 namespace ash {
 
 // A WTH used for unified desktop mode. This creates an offscreen
 // compositor whose texture will be copied into each displays'
 // compositor.
 class AshWindowTreeHostUnified : public AshWindowTreeHostPlatform,
                                  public aura::WindowObserver {
  public:
   explicit AshWindowTreeHostUnified(const gfx::Rect& initial_bounds);
   ~AshWindowTreeHostUnified() override;
@@ skipping 15 matching lines @@
   void OnWindowDestroying(aura::Window* window) override;
 
   std::vector<AshWindowTreeHost*> mirroring_hosts_;
 
   DISALLOW_COPY_AND_ASSIGN(AshWindowTreeHostUnified);
 };
 
 }  // namespace ash
 
 #endif  // ASH_HOST_ASH_WINDOW_TREE_HOST_UNIFIED_H_