[LayoutNG] Introduce NGPhysicalFragment and make NGFragment a 'view'

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

Index: third_party/WebKit/Source/core/layout/ng/ng_box.h
diff --git a/third_party/WebKit/Source/core/layout/ng/ng_box.h b/third_party/WebKit/Source/core/layout/ng/ng_box.h
index a2cd5647e6d69960ddb3226056f316114a50b3e7..d000b1b2abdb9e5a68a58bfbecbdafa56653ae35 100644
--- a/third_party/WebKit/Source/core/layout/ng/ng_box.h
+++ b/third_party/WebKit/Source/core/layout/ng/ng_box.h
@@ -16,6 +16,7 @@ class LayoutBox;
 class NGBlockLayoutAlgorithm;
 class NGConstraintSpace;
 class NGFragment;
+class NGPhysicalFragment;
 
 // Represents a node to be laid out.
 class CORE_EXPORT NGBox final : public GarbageCollected<NGBox> {
@@ -34,18 +35,21 @@ class CORE_EXPORT NGBox final : public GarbageCollected<NGBox> {
 
   NGBox* FirstChild() const;
 
+  DEFINE_INLINE_VIRTUAL_TRACE() {
+    visitor->trace(algorithm_);
+    visitor->trace(fragment_);
+  }
+
+ private:
   // This is necessary for interop between old and new trees -- after our parent
   // positions us, it calls this function so we can store the position on the
   // underlying LayoutBox.
-  void PositionUpdated(const NGFragment&);
-
-  DEFINE_INLINE_VIRTUAL_TRACE() { visitor->trace(algorithm_); }
-
- private:
+  void PositionUpdated();
   bool CanUseNewLayout();
 
   LayoutBox* layout_box_;
   Member<NGBlockLayoutAlgorithm> algorithm_;
+  Member<NGPhysicalFragment> fragment_;
 };
 
 }  // namespace blink