ui: Cleanup class/struct forward declarations

ui/ozone/platform/drm/mus_thread_proxy.h

 // Copyright 2016 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 UI_OZONE_PLATFORM_DRM_MUS_THREAD_PROXY_H_
 #define UI_OZONE_PLATFORM_DRM_MUS_THREAD_PROXY_H_
 
 #include "base/callback.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "base/observer_list.h"
 #include "base/synchronization/lock.h"
 #include "ui/gfx/native_widget_types.h"
 #include "ui/ozone/platform/drm/gpu/inter_thread_messaging_proxy.h"
 #include "ui/ozone/platform/drm/host/drm_cursor.h"
 #include "ui/ozone/platform/drm/host/gpu_thread_adapter.h"
 #include "ui/ozone/public/interfaces/device_cursor.mojom.h"
 
 namespace base {
 class SingleThreadTaskRunner;
 }
 
 namespace ui {
 
-class DrmCursor;
 class DrmDisplayHostManager;
 class DrmOverlayManager;
 class DrmThread;
 class GpuThreadObserver;
 class MusThreadProxy;
 
 // Forwarding proxy to handle ownership semantics.
 class CursorProxyThread : public DrmCursorProxy {
  public:
   explicit CursorProxyThread(MusThreadProxy* mus_thread_proxy);
@@ skipping 116 matching lines @@
   base::ThreadChecker on_window_server_thread_;
 
   base::WeakPtrFactory<MusThreadProxy> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(MusThreadProxy);
 };
 
 }  // namespace ui
 
 #endif  // UI_OZONE_PLATFORM_DRM_MUS_THREAD_PROXY_H_