[LayoutNG] Convert physical fragments to being RefCounted.

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

Index: third_party/WebKit/Source/core/layout/ng/ng_floating_object.h
diff --git a/third_party/WebKit/Source/core/layout/ng/ng_floating_object.h b/third_party/WebKit/Source/core/layout/ng/ng_floating_object.h
index 68a84315fb779c6785dd21e6f4895525e199adef..b8052bfcd9580d413fe9c45c290bd04d3cdbea52 100644
--- a/third_party/WebKit/Source/core/layout/ng/ng_floating_object.h
+++ b/third_party/WebKit/Source/core/layout/ng/ng_floating_object.h
@@ -18,7 +18,7 @@ class NGPhysicalFragment;
 
 // Struct that keeps all information needed to position floats in LayoutNG.
 struct CORE_EXPORT NGFloatingObject
-    : public GarbageCollected<NGFloatingObject> {
+    : public GarbageCollectedFinalized<NGFloatingObject> {
   NGFloatingObject(NGPhysicalFragment* fragment,
                    NGConstraintSpace* space,
                    NGBlockNode* node,
@@ -31,7 +31,7 @@ struct CORE_EXPORT NGFloatingObject
     clear_type = style.clear();
   }
 
-  Member<NGPhysicalFragment> fragment;
+  RefPtr<NGPhysicalFragment> fragment;
   // TODO(glebl): Constraint space should be const here.
   Member<NGConstraintSpace> space;
   Member<NGBlockNode> node;
@@ -40,7 +40,6 @@ struct CORE_EXPORT NGFloatingObject
   NGBoxStrut margins;
 
   DEFINE_INLINE_TRACE() {
-    visitor->trace(fragment);
     visitor->trace(space);
     visitor->trace(node);
   }