ui: Cleanup class/struct forward declarations

ui/ozone/platform/drm/host/drm_display_host_manager.h

 // Copyright 2014 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_HOST_DRM_DISPLAY_HOST_MANAGER_H_
 #define UI_OZONE_PLATFORM_DRM_HOST_DRM_DISPLAY_HOST_MANAGER_H_
 
 #include <stdint.h>
 
 #include <map>
@@ skipping 10 matching lines @@
 #include "ui/events/ozone/device/device_event_observer.h"
 #include "ui/events/ozone/evdev/event_factory_evdev.h"
 #include "ui/ozone/platform/drm/host/gpu_thread_observer.h"
 
 namespace ui {
 
 class DeviceManager;
 class DrmDeviceHandle;
 class DrmDisplayHost;
 class DrmDisplayHostManager;
-class DrmGpuPlatformSupportHost;
 class DrmNativeDisplayDelegate;
 class GpuThreadAdapter;
 
 struct DisplaySnapshot_Params;
 
 // The portion of the DrmDisplayHostManager implementation that is agnostic
 // in how its communication with GPU-specific functionality is implemented.
 // This is used from both the IPC and the in-process versions in  MUS.
 class DrmDisplayHostManager : public DeviceEventObserver, GpuThreadObserver {
  public:
@@ skipping 96 matching lines @@
   std::unique_ptr<DrmDeviceHandle> primary_drm_device_handle_;
 
   base::WeakPtrFactory<DrmDisplayHostManager> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(DrmDisplayHostManager);
 };
 
 }  // namespace ui
 
 #endif  // UI_OZONE_PLATFORM_DRM_HOST_DRM_DISPLAY_HOST_MANAGER_H_