Wire up CursorManager for DesktopWindowTreeHostMus

ui/aura/mus/window_port_mus.cc

Index: ui/aura/mus/window_port_mus.cc
diff --git a/ui/aura/mus/window_port_mus.cc b/ui/aura/mus/window_port_mus.cc
index 52985fe3d521b823447bbd33fa59c8f90992a814..d5a64e88c79980562c5792a140bbc36c9b926852 100644
--- a/ui/aura/mus/window_port_mus.cc
+++ b/ui/aura/mus/window_port_mus.cc
@@ -58,6 +58,9 @@ void WindowPortMus::SetImeVisibility(bool visible,
 }
 
 void WindowPortMus::SetPredefinedCursor(ui::mojom::Cursor cursor_id) {
+  if (cursor_id == predefined_cursor_)
+    return;
+
   window_tree_client_->SetPredefinedCursor(this, predefined_cursor_, cursor_id);
   predefined_cursor_ = cursor_id;
 }