remove leftover forward declaration of OnscreenDisplayClient

cc/surfaces/surface_display_output_surface.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 CC_SURFACES_SURFACE_DISPLAY_OUTPUT_SURFACE_H_
 #define CC_SURFACES_SURFACE_DISPLAY_OUTPUT_SURFACE_H_
 
 #include "base/macros.h"
 #include "base/threading/thread_checker.h"
 #include "cc/output/output_surface.h"
 #include "cc/surfaces/display_client.h"
 #include "cc/surfaces/surface_factory.h"
 #include "cc/surfaces/surface_factory_client.h"
 #include "cc/surfaces/surfaces_export.h"
 
 namespace cc {
 class Display;
-class OnscreenDisplayClient;
 class SurfaceIdAllocator;
 class SurfaceManager;
 
 // This class is maps a compositor OutputSurface to the surface system's Display
 // concept, allowing a compositor client to submit frames for a native root
 // window or physical display.
 class CC_SURFACES_EXPORT SurfaceDisplayOutputSurface
     : public OutputSurface,
       public SurfaceFactoryClient,
       public NON_EXPORTED_BASE(DisplayClient) {
@@ skipping 39 matching lines @@
   SurfaceId delegated_surface_id_;
   gfx::Size last_swap_frame_size_;
   bool output_surface_lost_ = false;
 
   DISALLOW_COPY_AND_ASSIGN(SurfaceDisplayOutputSurface);
 };
 
 }  // namespace cc
 
 #endif  // CC_SURFACES_SURFACE_DISPLAY_OUTPUT_SURFACE_H_