Implement aura::WindowPortMus::CreateCompositorFrameSink()

services/ui/ws/window_tree.cc

Index: services/ui/ws/window_tree.cc
diff --git a/services/ui/ws/window_tree.cc b/services/ui/ws/window_tree.cc
index 511a495c93d9e1159234e74f0a1f06b2825c9de6..b56b27da84ad29f03acc0f57c0e3dc107002ec30 100644
--- a/services/ui/ws/window_tree.cc
+++ b/services/ui/ws/window_tree.cc
@@ -2147,6 +2147,17 @@ void WindowTree::CancelWindowMove(Id window_id) {
       window_server_->GetCurrentMoveLoopChangeId());
 }
 
+void WindowTree::GetFrameSinkId(Id window_id,
+                                const GetFrameSinkIdCallback& callback) {
+  ServerWindow* window = GetWindowByClientId(ClientWindowId(window_id));
+  if (!window) {
+    DVLOG(1) << "GetFrameSinkId failed (invalid window id)";
+    callback.Run(base::Optional<cc::FrameSinkId>());
+    return;
+  }
+  callback.Run(window->frame_sink_id());
+}
+
 void WindowTree::AddAccelerators(
     std::vector<mojom::WmAcceleratorPtr> accelerators,
     const AddAcceleratorsCallback& callback) {