cc: Make most of cc::OutputSurface abstract.

services/ui/surfaces/direct_output_surface_ozone.h

Index: services/ui/surfaces/direct_output_surface_ozone.h
diff --git a/services/ui/surfaces/direct_output_surface_ozone.h b/services/ui/surfaces/direct_output_surface_ozone.h
index 29e785d80ff5c38c3b3be094fa8b0885d3e5d7e3..89fe2798a191aa8115e689c956175b5fb853f473 100644
--- a/services/ui/surfaces/direct_output_surface_ozone.h
+++ b/services/ui/surfaces/direct_output_surface_ozone.h
@@ -53,16 +53,22 @@ class DirectOutputSurfaceOzone : public cc::OutputSurface {
 
  private:
   // cc::OutputSurface implementation.
-  void SwapBuffers(cc::CompositorFrame frame) override;
+  bool BindToClient(cc::OutputSurfaceClient* client) override;
+  void EnsureBackbuffer() override;
+  void DiscardBackbuffer() override;
   void BindFramebuffer() override;
+  void SwapBuffers(cc::CompositorFrame frame) override;
   uint32_t GetFramebufferCopyTextureFormat() override;
   void Reshape(const gfx::Size& size,
                float scale_factor,
                const gfx::ColorSpace& color_space,
                bool alpha) override;
+  cc::OverlayCandidateValidator* GetOverlayCandidateValidator() const override;
   bool IsDisplayedAsOverlayPlane() const override;
   unsigned GetOverlayTextureId() const override;
-  bool BindToClient(cc::OutputSurfaceClient* client) override;
+  bool SurfaceIsSuspendForRecycle() const override;
+  bool HasExternalStencilTest() const override;
+  void ApplyExternalStencil() override;
 
   // Taken from BrowserCompositor specific API.
   void OnUpdateVSyncParametersFromGpu(base::TimeTicks timebase,