Implement aura::WindowPortMus::CreateCompositorFrameSink()

ui/aura/mus/window_tree_client.cc

Index: ui/aura/mus/window_tree_client.cc
diff --git a/ui/aura/mus/window_tree_client.cc b/ui/aura/mus/window_tree_client.cc
index 5244c70da3aab0a8c2835aa8be5d51270b5e3e41..2b35f96d90ef73c11ee86ca7bb8fbc56fd529100 100644
--- a/ui/aura/mus/window_tree_client.cc
+++ b/ui/aura/mus/window_tree_client.cc
@@ -947,6 +947,17 @@ void WindowTreeClient::StopPointerWatcher() {
   has_pointer_watcher_ = false;
 }
 
+cc::FrameSinkId WindowTreeClient::GetFrameSinkId(Id window_id) {
+  DCHECK(tree_);
+  base::Optional<cc::FrameSinkId> frame_sink_id;
+  mojo::SyncCallRestrictions::ScopedAllowSyncCall allow_sync_call;
+  if (!tree_->GetFrameSinkId(window_id, &frame_sink_id) || !frame_sink_id) {
+    DLOG(WARNING) << "GetFrameSinkId failed!";
+    return cc::FrameSinkId();
+  }
+  return *frame_sink_id;
+}
+
 void WindowTreeClient::AddObserver(WindowTreeClientObserver* observer) {
   observers_.AddObserver(observer);
 }