Add/remove surface references via MojoCompositorFrameSink.

services/ui/surfaces/display_compositor.h

Index: services/ui/surfaces/display_compositor.h
diff --git a/services/ui/surfaces/display_compositor.h b/services/ui/surfaces/display_compositor.h
index 7d9bc0084337ad2c30bc73636c4cbfa958d06275..1346bf1df422c7c36db0ff2b68c3474e885a6b57 100644
--- a/services/ui/surfaces/display_compositor.h
+++ b/services/ui/surfaces/display_compositor.h
@@ -60,6 +60,9 @@ class DisplayCompositor : public cc::SurfaceObserver,
       cc::mojom::DisplayCompositorClientPtr client);
   ~DisplayCompositor() override;
 
+  void AddSurfaceReference(const cc::SurfaceReference& ref);
+  void RemoveSurfaceReference(const cc::SurfaceReference& ref);
+
   // cc::mojom::DisplayCompositor implementation:
   void CreateCompositorFrameSink(
       const cc::FrameSinkId& frame_sink_id,
@@ -67,12 +70,6 @@ class DisplayCompositor : public cc::SurfaceObserver,
       cc::mojom::MojoCompositorFrameSinkRequest request,
       cc::mojom::MojoCompositorFrameSinkPrivateRequest private_request,
       cc::mojom::MojoCompositorFrameSinkClientPtr client) override;
-  void AddRootSurfaceReference(const cc::SurfaceId& child_id) override;
-  void AddSurfaceReference(const cc::SurfaceId& parent_id,
-                           const cc::SurfaceId& child_id) override;
-  void RemoveRootSurfaceReference(const cc::SurfaceId& child_id) override;
-  void RemoveSurfaceReference(const cc::SurfaceId& parent_id,
-                              const cc::SurfaceId& child_id) override;
 
   cc::SurfaceManager* manager() { return &manager_; }