Move FrameSink hierarchy registration to DisplayCompositor interface

components/display_compositor/gpu_root_compositor_frame_sink.h

 // Copyright 2017 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_DISPLAY_COMPOSITOR_GPU_ROOT_COMPOSITOR_FRAME_SINK_H_
 #define COMPONENTS_DISPLAY_COMPOSITOR_GPU_ROOT_COMPOSITOR_FRAME_SINK_H_
 
 #include "cc/ipc/display_compositor.mojom.h"
 #include "cc/ipc/mojo_compositor_frame_sink.mojom.h"
 #include "cc/surfaces/compositor_frame_sink_support_client.h"
@@ skipping 46 matching lines @@
   // cc::mojom::MojoCompositorFrameSink:
   void EvictFrame() override;
   void SetNeedsBeginFrame(bool needs_begin_frame) override;
   void SubmitCompositorFrame(const cc::LocalSurfaceId& local_surface_id,
                              cc::CompositorFrame frame) override;
   void Require(const cc::LocalSurfaceId& local_surface_id,
                const cc::SurfaceSequence& sequence) override;
   void Satisfy(const cc::SurfaceSequence& sequence) override;
 
   // cc::mojom::MojoCompositorFrameSinkPrivate:
-  void AddChildFrameSink(const cc::FrameSinkId& child_frame_sink_id) override;
-  void RemoveChildFrameSink(
-      const cc::FrameSinkId& child_frame_sink_id) override;
   void RequestCopyOfSurface(
       std::unique_ptr<cc::CopyOutputRequest> request) override;
 
  private:
   // cc::DisplayClient:
   void DisplayOutputSurfaceLost() override;
   void DisplayWillDrawAndSwap(bool will_draw_and_swap,
                               const cc::RenderPassList& render_passes) override;
   void DisplayDidDrawAndSwap() override;
 
@@ skipping 24 matching lines @@
   mojo::Binding<cc::mojom::MojoCompositorFrameSinkPrivate>
       compositor_frame_sink_private_binding_;
   mojo::AssociatedBinding<cc::mojom::DisplayPrivate> display_private_binding_;
 
   DISALLOW_COPY_AND_ASSIGN(GpuRootCompositorFrameSink);
 };
 
 }  // namespace display_compositor
 
 #endif  // COMPONENTS_DISPLAY_COMPOSITOR_GPU_ROOT_COMPOSITOR_FRAME_SINK_H_