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

ui/accessibility/tree_generator.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 "ui/accessibility/tree_generator.h"
 
 #include "ui/accessibility/ax_serializable_tree.h"
 #include "ui/accessibility/ax_tree.h"
 
 namespace ui {
@@ skipping 70 matching lines @@
     for (int i = 0; i < node_count; ++i)
       permuted.push_back(i + 1);
   }
 
   // Build an AXTreeUpdate. The first two nodes of the tree always
   // go in the same place.
   AXTreeUpdate update;
   update.root_id = permuted[0];
   update.nodes.resize(node_count);
   update.nodes[0].id = permuted[0];
-  update.nodes[0].state = AX_STATE_NONE;
+  update.nodes[0].ClearBitfields();
   if (node_count > 1) {
     update.nodes[0].child_ids.push_back(permuted[1]);
     update.nodes[1].id = permuted[1];
-    update.nodes[1].state = AX_STATE_NONE;
+    update.nodes[1].ClearBitfields();
   }
 
   // The remaining nodes are assigned based on their parent
   // selected from the next bits from |tree_index|.
   for (int i = 2; i < node_count; ++i) {
     update.nodes[i].id = permuted[i];
-    update.nodes[i].state = AX_STATE_NONE;
+    update.nodes[i].ClearBitfields();
     int parent_index = (tree_index % i);
     tree_index /= i;
     update.nodes[parent_index].child_ids.push_back(permuted[i]);
   }
 
   // Unserialize the tree update into the destination tree.
   CHECK(out_tree->Unserialize(update)) << out_tree->error();
 };
 
 }  // namespace ui