Refactor content/renderer/accessibility to use AXTreeSerializer (re-land).

ui/accessibility/ax_tree_serializer.h

Index: ui/accessibility/ax_tree_serializer.h
diff --git a/ui/accessibility/ax_tree_serializer.h b/ui/accessibility/ax_tree_serializer.h
index c5f2c0dd8fc745fc21fdbbf1ebdd2466b675fa9c..9c735e0118db1d9cb21b351a16b4b92b78e73ddf 100644
--- a/ui/accessibility/ax_tree_serializer.h
+++ b/ui/accessibility/ax_tree_serializer.h
@@ -172,10 +172,13 @@ AXTreeSerializer<AXSourceNode>::~AXTreeSerializer() {
 
 template<typename AXSourceNode>
 void AXTreeSerializer<AXSourceNode>::Reset() {
-  if (client_root_) {
-    DeleteClientSubtree(client_root_);
-    client_root_ = NULL;
-  }
+  if (!client_root_)
+    return;
+
+  DeleteClientSubtree(client_root_);
+  client_id_map_.erase(client_root_->id);
+  delete client_root_;
+  client_root_ = NULL;
 }
 
 template<typename AXSourceNode>
@@ -305,9 +308,7 @@ void AXTreeSerializer<AXSourceNode>::SerializeChanges(
       // If there's no LCA, just tell the client to destroy the whole
       // tree and then we'll serialize everything from the new root.
       out_update->node_id_to_clear = client_root_->id;
-      DeleteClientSubtree(client_root_);
-      client_id_map_.erase(client_root_->id);
-      client_root_ = NULL;
+      Reset();
     } else if (need_delete) {
       // Otherwise, if we need to reserialize a subtree, first we need
       // to delete those nodes in our client tree so that
@@ -318,6 +319,7 @@ void AXTreeSerializer<AXSourceNode>::SerializeChanges(
       for (size_t i = 0; i < client_lca->children.size(); ++i) {
         client_id_map_.erase(client_lca->children[i]->id);
         DeleteClientSubtree(client_lca->children[i]);
+        delete client_lca->children[i];
       }
       client_lca->children.clear();
     }
@@ -342,6 +344,7 @@ void AXTreeSerializer<AXSourceNode>::DeleteClientSubtree(
   for (size_t i = 0; i < client_node->children.size(); ++i) {
     client_id_map_.erase(client_node->children[i]->id);
     DeleteClientSubtree(client_node->children[i]);
+    delete client_node->children[i];
   }
   client_node->children.clear();
 }
@@ -365,10 +368,7 @@ void AXTreeSerializer<AXSourceNode>::SerializeChangedNodes(
   int id = tree_->GetId(node);
   ClientTreeNode* client_node = ClientTreeNodeById(id);
   if (!client_node) {
-    if (client_root_) {
-      client_id_map_.erase(client_root_->id);
-      DeleteClientSubtree(client_root_);
-    }
+    Reset();
     client_root_ = new ClientTreeNode();
     client_node = client_root_;
     client_node->id = id;
@@ -408,6 +408,7 @@ void AXTreeSerializer<AXSourceNode>::SerializeChangedNodes(
     if (new_child_ids.find(old_child_id) == new_child_ids.end()) {
       client_id_map_.erase(old_child_id);
       DeleteClientSubtree(old_child);
+      delete old_child;
     } else {
       client_child_id_map[old_child_id] = old_child;
     }