Add a treeChange type to Automation

ui/accessibility/ax_tree.cc

Index: ui/accessibility/ax_tree.cc
diff --git a/ui/accessibility/ax_tree.cc b/ui/accessibility/ax_tree.cc
index bd879eaac441754030ef96bae00cdbec65370f2d..3958a4db241d5dc5d4a784679c412f4c1c275774 100644
--- a/ui/accessibility/ax_tree.cc
+++ b/ui/accessibility/ax_tree.cc
@@ -113,10 +113,27 @@ bool AXTree::Unserialize(const AXTreeUpdate& update) {
       update_state.pending_nodes.insert(node);
     }
   }
-
+  std::set<int> node_created_ids;
+  std::set<int> text_changed_ids;
   for (size_t i = 0; i < update.nodes.size(); ++i) {
+    AXNode* original_node = GetFromId(update.nodes[i].id);
+    std::string original_text;
+    if (original_node)
+      original_text = original_node->data().GetStringAttribute(AX_ATTR_NAME);
+
     if (!UpdateNode(update.nodes[i], &update_state))
       return false;
+
+    AXNode* updated_node = GetFromId(update.nodes[i].id);
+    std::string updated_text;
+    if (updated_node)
+      updated_text = updated_node->data().GetStringAttribute(AX_ATTR_NAME);
+    if (!original_node && updated_node)
+      node_created_ids.insert(update.nodes[i].id);
+    if (!original_text.empty() && !updated_text.empty() &&
+        updated_text != original_text) {
+      text_changed_ids.insert(update.nodes[i].id);
+    }
   }
 
   if (!update_state.pending_nodes.empty()) {
@@ -139,12 +156,22 @@ bool AXTree::Unserialize(const AXTreeUpdate& update) {
           changes.push_back(
               AXTreeDelegate::Change(node, AXTreeDelegate::SUBTREE_CREATED));
         } else {
-          changes.push_back(
-              AXTreeDelegate::Change(node, AXTreeDelegate::NODE_CREATED));
+          // Node creation based on |new_nodes| is sometimes unreliable. Define
+          // creation based on this tree.
+          if (node_created_ids.find(node->data().id) !=
+              node_created_ids.end()) {
+            changes.push_back(
+                AXTreeDelegate::Change(node, AXTreeDelegate::NODE_CREATED));
+          }
         }
       } else {
-        changes.push_back(
-            AXTreeDelegate::Change(node, AXTreeDelegate::NODE_CHANGED));
+        if (text_changed_ids.find(node->data().id) == text_changed_ids.end()) {
+          changes.push_back(
+              AXTreeDelegate::Change(node, AXTreeDelegate::NODE_CHANGED));
+        } else {
+          changes.push_back(
+              AXTreeDelegate::Change(node, AXTreeDelegate::TEXT_CHANGED));
+        }
       }
     }
     delegate_->OnAtomicUpdateFinished(