Move NGLayoutOpportunityTreeNode off Oilpan

third_party/WebKit/Source/core/layout/ng/ng_layout_opportunity_tree_node.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 "core/layout/ng/ng_layout_opportunity_tree_node.h"
 
 namespace blink {
 
 NGLayoutOpportunityTreeNode::NGLayoutOpportunityTreeNode(
     const NGLogicalRect opportunity)
@@ skipping 10 matching lines @@
       combined_exclusion(nullptr) {}
 
 String NGLayoutOpportunityTreeNode::ToString() const {
   return String::format("Opportunity: '%s' Exclusion: '%s'",
                         opportunity.ToString().ascii().data(),
                         combined_exclusion
                             ? combined_exclusion->ToString().ascii().data()
                             : "null");
 }
 
-DEFINE_TRACE(NGLayoutOpportunityTreeNode) {
-  visitor->trace(left);
-  visitor->trace(bottom);
-  visitor->trace(right);
-}
-
 }  // namespace blink