content: Cleanup class/struct forward declarations

content/browser/compositor/browser_compositor_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 CONTENT_BROWSER_COMPOSITOR_BROWSER_COMPOSITOR_OUTPUT_SURFACE_H_
 #define CONTENT_BROWSER_COMPOSITOR_BROWSER_COMPOSITOR_OUTPUT_SURFACE_H_
 
 #include "base/macros.h"
 #include "base/threading/non_thread_safe.h"
 #include "build/build_config.h"
 #include "cc/output/output_surface.h"
 #include "content/common/content_export.h"
 #include "ui/compositor/compositor_vsync_manager.h"
 
 namespace cc {
 class SoftwareOutputDevice;
 class SyntheticBeginFrameSource;
 }
 
 namespace display_compositor {
 class CompositorOverlayCandidateValidator;
 }
 
 namespace gfx {
 enum class SwapResult;
 }
 
-namespace gpu {
-struct GpuProcessHostedCALayerTreeParamsMac;
-}
-
 namespace content {
-class ContextProviderCommandBuffer;
 class ReflectorImpl;
-class WebGraphicsContext3DCommandBufferImpl;
 
 class CONTENT_EXPORT BrowserCompositorOutputSurface
     : public cc::OutputSurface {
  public:
   ~BrowserCompositorOutputSurface() override;
 
   // cc::OutputSurface implementation.
   cc::OverlayCandidateValidator* GetOverlayCandidateValidator() const override;
   bool HasExternalStencilTest() const override;
   void ApplyExternalStencil() override;
@@ skipping 38 matching lines @@
  private:
   std::unique_ptr<display_compositor::CompositorOverlayCandidateValidator>
       overlay_candidate_validator_;
 
   DISALLOW_COPY_AND_ASSIGN(BrowserCompositorOutputSurface);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_COMPOSITOR_BROWSER_COMPOSITOR_OUTPUT_SURFACE_H_