Move NGLayoutOpportunityTreeNode off Oilpan

BUG=635619

Review-Url: https://codereview.chromium.org/2750153003
Cr-Commit-Position: refs/heads/master@{#457533}

third_party/WebKit/Source/core/layout/ng/ng_layout_opportunity_iterator.cc

@@ -32,13 +32,13 @@ void AppendNodeToString(const NGLayoutOpportunityTreeNode* node,
 
   string_builder->append(indent_builder.toString());
   string_builder->append("Left:\t");
-  AppendNodeToString(node->left, string_builder, indent + 2);
+  AppendNodeToString(node->left.get(), string_builder, indent + 2);
   string_builder->append(indent_builder.toString());
   string_builder->append("Right:\t");
-  AppendNodeToString(node->right, string_builder, indent + 2);
+  AppendNodeToString(node->right.get(), string_builder, indent + 2);
   string_builder->append(indent_builder.toString());
   string_builder->append("Bottom:\t");
-  AppendNodeToString(node->bottom, string_builder, indent + 2);
+  AppendNodeToString(node->bottom.get(), string_builder, indent + 2);
 }
 
 // Collects all opportunities from leaves of Layout Opportunity spatial tree.
@@ -48,9 +48,9 @@ void CollectAllOpportunities(const NGLayoutOpportunityTreeNode* node,
     return;
   if (node->IsLeafNode())
     opportunities.push_back(node->opportunity);
-  CollectAllOpportunities(node->left, opportunities);
-  CollectAllOpportunities(node->bottom, opportunities);
-  CollectAllOpportunities(node->right, opportunities);
+  CollectAllOpportunities(node->left.get(), opportunities);
+  CollectAllOpportunities(node->bottom.get(), opportunities);
+  CollectAllOpportunities(node->right.get(), opportunities);
 }
 
 // Creates layout opportunity from the provided space and the origin point.
@@ -161,9 +161,9 @@ NGLayoutOpportunityTreeNode* CreateRightNGLayoutOpportunityTreeNode(
 
 void SplitNGLayoutOpportunityTreeNode(const NGLogicalRect& rect,
                                       NGLayoutOpportunityTreeNode* node) {
-  node->left = CreateLeftNGLayoutOpportunityTreeNode(node, rect);
-  node->right = CreateRightNGLayoutOpportunityTreeNode(node, rect);
-  node->bottom = CreateBottomNGLayoutOpportunityTreeNode(node, rect);
+  node->left.reset(CreateLeftNGLayoutOpportunityTreeNode(node, rect));
+  node->right.reset(CreateRightNGLayoutOpportunityTreeNode(node, rect));
+  node->bottom.reset(CreateBottomNGLayoutOpportunityTreeNode(node, rect));
 }
 
 // Gets/Creates the "TOP" positioned constraint space by splitting
@@ -222,9 +222,9 @@ void InsertExclusion(NGLayoutOpportunityTreeNode* node,
     SplitNGLayoutOpportunityTreeNode(node->combined_exclusion->rect, node);
     node->exclusions.push_back(exclusion);
   } else {
-    InsertExclusion(node->left, exclusion, opportunities);
-    InsertExclusion(node->bottom, exclusion, opportunities);
-    InsertExclusion(node->right, exclusion, opportunities);
+    InsertExclusion(node->left.get(), exclusion, opportunities);
+    InsertExclusion(node->bottom.get(), exclusion, opportunities);
+    InsertExclusion(node->right.get(), exclusion, opportunities);
   }
 }
 
@@ -288,7 +288,8 @@ NGLayoutOpportunityIterator::NGLayoutOpportunityIterator(
 
   NGLayoutOpportunity initial_opportunity =
       CreateLayoutOpportunityFromConstraintSpace(*constraint_space_, Offset());
-  opportunity_tree_root_ = new NGLayoutOpportunityTreeNode(initial_opportunity);
+  opportunity_tree_root_.reset(
+      new NGLayoutOpportunityTreeNode(initial_opportunity));
 
   if (opt_leader_point) {
     const NGExclusion leader_exclusion =

third_party/WebKit/Source/core/layout/ng/ng_layout_opportunity_iterator.h

@@ -7,7 +7,6 @@
 
 #include "core/CoreExport.h"
 #include "core/layout/ng/ng_layout_opportunity_tree_node.h"
-#include "platform/heap/Handle.h"
 #include "wtf/Optional.h"
 #include "wtf/Vector.h"
 #include "wtf/text/StringBuilder.h"
@@ -63,7 +62,7 @@ class CORE_EXPORT NGLayoutOpportunityIterator final {
 
   NGLayoutOpportunities opportunities_;
   NGLayoutOpportunities::const_iterator opportunity_iter_;
-  Persistent<NGLayoutOpportunityTreeNode> opportunity_tree_root_;
+  std::unique_ptr<NGLayoutOpportunityTreeNode> opportunity_tree_root_;
   NGLogicalOffset offset_;
 };
 

third_party/WebKit/Source/core/layout/ng/ng_layout_opportunity_tree_node.cc

@@ -28,10 +28,4 @@ String NGLayoutOpportunityTreeNode::ToString() const {
                             : "null");
 }
 
-DEFINE_TRACE(NGLayoutOpportunityTreeNode) {
-  visitor->trace(left);
-  visitor->trace(bottom);
-  visitor->trace(right);
-}
-
 }  // namespace blink

third_party/WebKit/Source/core/layout/ng/ng_layout_opportunity_tree_node.h

@@ -8,15 +8,13 @@
 #include "core/layout/ng/geometry/ng_edge.h"
 #include "core/layout/ng/geometry/ng_logical_rect.h"
 #include "core/layout/ng/ng_exclusion.h"
-#include "platform/heap/Handle.h"
 
 namespace blink {
 
 // 3 node R-Tree that represents available space(left, bottom, right) or
 // layout opportunity after the parent spatial rectangle is split by the
 // exclusion rectangle.
-struct CORE_EXPORT NGLayoutOpportunityTreeNode
-    : public GarbageCollectedFinalized<NGLayoutOpportunityTreeNode> {
+struct CORE_EXPORT NGLayoutOpportunityTreeNode {
  public:
   // Default constructor.
   // Creates a Layout Opportunity tree node that is limited by it's own edge
@@ -31,9 +29,9 @@ struct CORE_EXPORT NGLayoutOpportunityTreeNode
                               NGEdge exclusion_edge);
 
   // Children of the node.
-  Member<NGLayoutOpportunityTreeNode> left;
-  Member<NGLayoutOpportunityTreeNode> bottom;
-  Member<NGLayoutOpportunityTreeNode> right;
+  std::unique_ptr<NGLayoutOpportunityTreeNode> left;
+  std::unique_ptr<NGLayoutOpportunityTreeNode> bottom;
+  std::unique_ptr<NGLayoutOpportunityTreeNode> right;
 
   // The top layout opportunity associated with this node.
   NGLogicalRect opportunity;
@@ -53,8 +51,6 @@ struct CORE_EXPORT NGLayoutOpportunityTreeNode
   bool IsLeafNode() const { return exclusions.isEmpty(); }
 
   String ToString() const;
-
-  DECLARE_TRACE();
 };
 
 inline std::ostream& operator<<(std::ostream& stream,