[cpp20] Fix incompatible aggregate initialization

third_party/accessibility/ax/ax_tree_update.h

diff --git a/third_party/accessibility/ax/ax_tree_update.h b/third_party/accessibility/ax/ax_tree_update.h
index e0b895f..c480469 100644
--- a/third_party/accessibility/ax/ax_tree_update.h
+++ b/third_party/accessibility/ax/ax_tree_update.h
@@ -50,7 +50,6 @@
 //        before or after an AXTreeUpdate.
 template <typename AXNodeData, typename AXTreeData>
 struct AXTreeUpdateBase {
-  AXTreeUpdateBase() = default;
   ~AXTreeUpdateBase() = default;
 
   // If |has_tree_data| is true, the value of |tree_data| should be used