Automatically fire AX events on Mac based on tree changes

ui/accessibility/ax_tree.h

 // Copyright 2013 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.
 
 #ifndef UI_ACCESSIBILITY_AX_TREE_H_
 #define UI_ACCESSIBILITY_AX_TREE_H_
 
 #include <stdint.h>
 
 #include <set>
@@ skipping 67 matching lines @@
                                       AXBoolAttribute attr,
                                       bool new_value) {}
   virtual void OnIntListAttributeChanged(
       AXTree* tree,
       AXNode* node,
       AXIntListAttribute attr,
       const std::vector<int32_t>& old_value,
       const std::vector<int32_t>& new_value) {}
 
   // Called when tree data changes.
-  virtual void OnTreeDataChanged(AXTree* tree) = 0;
-
+  virtual void OnTreeDataChanged(AXTree* tree,
+                                 const ui::AXTreeData& old_data,
+                                 const ui::AXTreeData& new_data) = 0;
   // Called just before a node is deleted. Its id and data will be valid,
   // but its links to parents and children are invalid. This is called
   // in the middle of an update, the tree may be in an invalid state!
   virtual void OnNodeWillBeDeleted(AXTree* tree, AXNode* node) = 0;
 
   // Same as OnNodeWillBeDeleted, but only called once for an entire subtree.
   // This is called in the middle of an update, the tree may be in an
   // invalid state!
   virtual void OnSubtreeWillBeDeleted(AXTree* tree, AXNode* node) = 0;
 
@@ skipping 123 matching lines @@
   AXTreeDelegate* delegate_;
   AXNode* root_;
   base::hash_map<int32_t, AXNode*> id_map_;
   std::string error_;
   AXTreeData data_;
 };
 
 }  // namespace ui
 
 #endif  // UI_ACCESSIBILITY_AX_TREE_H_