ui: Cleanup class/struct forward declarations

ui/ozone/platform/drm/gpu/drm_thread.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 UI_OZONE_PLATFORM_DRM_GPU_DRM_THREAD_H_
 #define UI_OZONE_PLATFORM_DRM_GPU_DRM_THREAD_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 13 matching lines @@
 
 namespace base {
 struct FileDescriptor;
 }
 
 namespace gfx {
 class Point;
 class Rect;
 }
 
-namespace service_manager {
-class Connection;
-}
-
 namespace ui {
 
 class DrmDeviceManager;
 class DrmGpuDisplayManager;
-class DrmWindow;
-class DrmWindowProxy;
 class GbmBuffer;
 class ScanoutBufferGenerator;
 class ScreenManager;
 
 struct GammaRampRGBEntry;
 struct OverlayPlane;
 
 // Holds all the DRM related state and performs all DRM related operations.
 //
 // The DRM thread is used to insulate DRM operations from potential blocking
@@ skipping 87 matching lines @@
   // The mojo implementation requires a BindingSet because the DrmThread serves
   // requests from two different client threads.
   mojo::BindingSet<ozone::mojom::DeviceCursor> bindings_;
 
   DISALLOW_COPY_AND_ASSIGN(DrmThread);
 };
 
 }  // namespace ui
 
 #endif  // UI_OZONE_PLATFORM_DRM_GPU_DRM_THREAD_H_