Move FrameSink hierarchy registration to DisplayCompositor interface

components/display_compositor/gpu_root_compositor_frame_sink.cc

 // 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.
 
 #include "components/display_compositor/gpu_root_compositor_frame_sink.h"
 
 #include "cc/surfaces/compositor_frame_sink_support.h"
 #include "cc/surfaces/display.h"
 
 namespace display_compositor {
@@ skipping 81 matching lines @@
 void GpuRootCompositorFrameSink::Require(
     const cc::LocalSurfaceId& local_surface_id,
     const cc::SurfaceSequence& sequence) {
   support_->Require(local_surface_id, sequence);
 }
 
 void GpuRootCompositorFrameSink::Satisfy(const cc::SurfaceSequence& sequence) {
   support_->Satisfy(sequence);
 }
 
-void GpuRootCompositorFrameSink::AddChildFrameSink(
-    const cc::FrameSinkId& child_frame_sink_id) {
-  support_->AddChildFrameSink(child_frame_sink_id);
-}
-
-void GpuRootCompositorFrameSink::RemoveChildFrameSink(
-    const cc::FrameSinkId& child_frame_sink_id) {
-  support_->RemoveChildFrameSink(child_frame_sink_id);
-}
-
 void GpuRootCompositorFrameSink::RequestCopyOfSurface(
     std::unique_ptr<cc::CopyOutputRequest> request) {
   support_->RequestCopyOfSurface(std::move(request));
 }
 
 void GpuRootCompositorFrameSink::DisplayOutputSurfaceLost() {
   // TODO(staraz): Implement this. Client should hear about context/output
   // surface lost.
 }
 
@@ skipping 34 matching lines @@
 }
 
 void GpuRootCompositorFrameSink::OnPrivateConnectionLost() {
   private_connection_lost_ = true;
   // Request destruction of |this| only if both connections are lost.
   delegate_->OnPrivateConnectionLost(support_->frame_sink_id(),
                                      client_connection_lost_);
 }
 
 }  // namespace display_compositor