Impl mus::mojom::GpuService to enable using Chrome IPC version gpu CmdBuf in mus

components/mus/public/cpp/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 COMPONENTS_MUS_PUBLIC_CPP_OUTPUT_SURFACE_H_
 #define COMPONENTS_MUS_PUBLIC_CPP_OUTPUT_SURFACE_H_
 
 #include "base/macros.h"
 #include "cc/output/output_surface.h"
 #include "cc/surfaces/surface_id.h"
+#include "components/mus/public/cpp/mus_public_export.h"
 #include "components/mus/public/cpp/window_surface.h"
 #include "components/mus/public/cpp/window_surface_client.h"
 #include "mojo/public/cpp/bindings/binding.h"
 
 namespace mus {
 
-class OutputSurface : public cc::OutputSurface, public WindowSurfaceClient {
+class MUS_PUBLIC_EXPORT OutputSurface : public cc::OutputSurface,
+                                        public WindowSurfaceClient {
  public:
   OutputSurface(const scoped_refptr<cc::ContextProvider>& context_provider,
                 std::unique_ptr<WindowSurface> surface);
   ~OutputSurface() override;
 
   // cc::OutputSurface implementation.
   void SwapBuffers(cc::CompositorFrame* frame) override;
   bool BindToClient(cc::OutputSurfaceClient* client) override;
   void DetachFromClient() override;
 
  private:
   // WindowSurfaceClient implementation:
   void OnResourcesReturned(
       WindowSurface* surface,
       mojo::Array<mojom::ReturnedResourcePtr> resources) override;
 
   void SwapBuffersComplete();
 
   std::unique_ptr<WindowSurface> surface_;
 
   DISALLOW_COPY_AND_ASSIGN(OutputSurface);
 };
 
 }  // namespace mus
 
 #endif  // COMPONENTS_MUS_PUBLIC_CPP_OUTPUT_SURFACE_H_