A11y: Add/refactor methods for manipulating bitfields on AXNodeData.

chrome/browser/ui/aura/accessibility/ax_tree_source_aura.cc

 // Copyright 2014 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 "chrome/browser/ui/aura/accessibility/ax_tree_source_aura.h"
 
 #include <stddef.h>
 
 #include <vector>
 
@@ skipping 105 matching lines @@
     if (rfh) {
       int ax_tree_id = rfh->GetAXTreeID();
       out_data->AddIntAttribute(ui::AX_ATTR_CHILD_TREE_ID, ax_tree_id);
     }
   }
 }
 
 std::string AXTreeSourceAura::ToString(AXAuraObjWrapper* root,
                                        std::string prefix) {
   ui::AXNodeData data;
+  data.ClearBitfields();
   root->Serialize(&data);
   std::string output = prefix + data.ToString() + '\n';
 
   std::vector<AXAuraObjWrapper*> children;
   root->GetChildren(&children);
 
   prefix += prefix[0];
   for (size_t i = 0; i < children.size(); ++i)
     output += ToString(children[i], prefix);
 
   return output;
 }