ui: Cleanup class/struct forward declarations

ui/ozone/platform/drm/gpu/gbm_surface_factory.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_GPU_GBM_SURFACE_FACTORY_H_
 #define UI_OZONE_PLATFORM_DRM_GPU_GBM_SURFACE_FACTORY_H_
 
 #include <stdint.h>
 
 #include <map>
 #include <memory>
 #include <vector>
 
 #include "base/macros.h"
 #include "base/threading/thread_checker.h"
 #include "ui/gl/gl_implementation.h"
 #include "ui/gl/gl_surface.h"
 #include "ui/ozone/common/gl_ozone_egl.h"
 #include "ui/ozone/public/surface_factory_ozone.h"
 
 namespace ui {
 
 class DrmThreadProxy;
-class GbmDevice;
 class GbmSurfaceless;
 
 class GbmSurfaceFactory : public SurfaceFactoryOzone {
  public:
   explicit GbmSurfaceFactory(DrmThreadProxy* drm_thread_proxy);
   ~GbmSurfaceFactory() override;
 
   void RegisterSurface(gfx::AcceleratedWidget widget, GbmSurfaceless* surface);
   void UnregisterSurface(gfx::AcceleratedWidget widget);
   GbmSurfaceless* GetSurface(gfx::AcceleratedWidget widget) const;
@@ skipping 25 matching lines @@
   DrmThreadProxy* drm_thread_proxy_;
 
   std::map<gfx::AcceleratedWidget, GbmSurfaceless*> widget_to_surface_map_;
 
   DISALLOW_COPY_AND_ASSIGN(GbmSurfaceFactory);
 };
 
 }  // namespace ui
 
 #endif  // UI_OZONE_PLATFORM_DRM_GPU_GBM_SURFACE_FACTORY_H_