Fix index used to join results of DOM.getDocument and CSS.getLayoutTreeAndStyles

headless/public/util/dom_tree_extractor.cc

 // Copyright 2016 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 "headless/public/util/dom_tree_extractor.h"
 
 #include "base/bind.h"
 #include "base/json/json_writer.h"
 #include "headless/public/headless_devtools_client.h"
 
@@ skipping 67 matching lines @@
     for (const std::unique_ptr<dom::Node>& child : *node->GetChildren()) {
       EnumerateNodes(child.get());
     }
   }
 }
 
 void DomTreeExtractor::ExtractLayoutTreeNodes() {
   dom_tree_.layout_tree_nodes_.reserve(
       dom_tree_.layout_tree_and_styles_result_->GetLayoutTreeNodes()->size());
 
-  // Only extract layout tree nodes that map to a DOM node.
   for (const std::unique_ptr<css::LayoutTreeNode>& layout_node :
        *dom_tree_.layout_tree_and_styles_result_->GetLayoutTreeNodes()) {
     std::unordered_map<NodeId, size_t>::const_iterator it =
-        dom_tree_.node_id_to_index_.find(layout_node->GetBackendNodeId());
-    if (it == dom_tree_.node_id_to_index_.end())
-      continue;
-
+        dom_tree_.node_id_to_index_.find(layout_node->GetNodeId());
+    DCHECK(it != dom_tree_.node_id_to_index_.end());
     dom_tree_.layout_tree_nodes_.push_back(layout_node.get());
   }
 }
 
 void DomTreeExtractor::ExtractComputedStyles() {
   dom_tree_.computed_styles_.reserve(
       dom_tree_.layout_tree_and_styles_result_->GetComputedStyles()->size());
 
   for (const std::unique_ptr<css::ComputedStyle>& computed_style :
        *dom_tree_.layout_tree_and_styles_result_->GetComputedStyles()) {
     dom_tree_.computed_styles_.push_back(computed_style.get());
   }
 }
 
 DomTreeExtractor::DomTree::DomTree() {}
 DomTreeExtractor::DomTree::~DomTree() {}
 
 DomTreeExtractor::DomTree::DomTree(DomTree&& other) = default;
 
 }  // namespace headless