Automatically fire AX events on Mac based on tree changes

ui/accessibility/ax_tree_fuzzer.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/accessibility/ax_tree.h"
 
 class EmptyAXTreeDelegate : public ui::AXTreeDelegate {
  public:
   EmptyAXTreeDelegate() {}
 
   void OnNodeDataWillChange(ui::AXTree* tree,
                             const ui::AXNodeData& old_node_data,
                             const ui::AXNodeData& new_node_data) override {}
-  void OnTreeDataChanged(ui::AXTree* tree) override {}
+  void OnTreeDataChanged(ui::AXTree* tree,
+                         const ui::AXTreeData& old_data,
+                         const ui::AXTreeData& new_data) override {}
   void OnNodeWillBeDeleted(ui::AXTree* tree, ui::AXNode* node) override {}
   void OnSubtreeWillBeDeleted(ui::AXTree* tree, ui::AXNode* node) override {}
   void OnNodeWillBeReparented(ui::AXTree* tree, ui::AXNode* node) override {}
   void OnSubtreeWillBeReparented(ui::AXTree* tree, ui::AXNode* node) override {}
   void OnNodeCreated(ui::AXTree* tree, ui::AXNode* node) override {}
   void OnNodeReparented(ui::AXTree* tree, ui::AXNode* node) override {}
   void OnNodeChanged(ui::AXTree* tree, ui::AXNode* node) override {}
   void OnAtomicUpdateFinished(ui::AXTree* tree,
                               bool root_changed,
                               const std::vector<Change>& changes) override {}
@@ skipping 17 matching lines @@
   // Run with --v=1 to aid in debugging a specific crash.
   VLOG(1) << "Input accessibility tree:\n" << initial_state.ToString();
 
   EmptyAXTreeDelegate delegate;
   ui::AXTree tree;
   tree.SetDelegate(&delegate);
   tree.Unserialize(initial_state);
 
   return 0;
 }