Move FrameSink hierarchy registration to DisplayCompositor interface

components/display_compositor/gpu_compositor_frame_sink.cc

Index: components/display_compositor/gpu_compositor_frame_sink.cc
diff --git a/components/display_compositor/gpu_compositor_frame_sink.cc b/components/display_compositor/gpu_compositor_frame_sink.cc
index 58b833dfe56cf8cc01f8c306715ed15634c85caf..ce450b6e612ba9ec62fbc21700914dfebcc04c79 100644
--- a/components/display_compositor/gpu_compositor_frame_sink.cc
+++ b/components/display_compositor/gpu_compositor_frame_sink.cc
@@ -66,16 +66,6 @@ void GpuCompositorFrameSink::DidReceiveCompositorFrameAck() {
     client_->DidReceiveCompositorFrameAck();
 }
 
-void GpuCompositorFrameSink::AddChildFrameSink(
-    const cc::FrameSinkId& child_frame_sink_id) {
-  support_->AddChildFrameSink(child_frame_sink_id);
-}
-
-void GpuCompositorFrameSink::RemoveChildFrameSink(
-    const cc::FrameSinkId& child_frame_sink_id) {
-  support_->RemoveChildFrameSink(child_frame_sink_id);
-}
-
 void GpuCompositorFrameSink::RequestCopyOfSurface(
     std::unique_ptr<cc::CopyOutputRequest> request) {
   support_->RequestCopyOfSurface(std::move(request));