Make NGFragment to own NGPhysicalFragment

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

 // 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.
 
 #ifndef NGPhysicalFragment_h
 #define NGPhysicalFragment_h
 
 #include "core/CoreExport.h"
 #include "core/layout/ng/ng_physical_fragment_base.h"
 #include "core/layout/ng/ng_units.h"
 #include "platform/heap/Handle.h"
 #include "wtf/Vector.h"
 
 namespace blink {
 
 class CORE_EXPORT NGPhysicalFragment final : public NGPhysicalFragmentBase {
  public:
   // This modifies the passed-in children vector.
   NGPhysicalFragment(NGPhysicalSize size,
                      NGPhysicalSize overflow,
-                     HeapVector<Member<const NGPhysicalFragmentBase>>& children,
+                     Vector<const NGPhysicalFragmentBase*>& children,
                      NGMarginStrut margin_strut)
       : NGPhysicalFragmentBase(size, overflow, FragmentBox, margin_strut) {
     children_.swap(children);
   }
 
-  const HeapVector<Member<const NGPhysicalFragmentBase>>& Children() const {
+  const Vector<const NGPhysicalFragmentBase*>& Children() const {
     return children_;

[cbiesinger, 2016/09/26 17:17:55]

I really think you should document in the builder & in the header of this file
that the child fragments need to be kept alive by the caller as this class just
keeps a pointer to them. that's pretty subtle...

   }
 
-  DEFINE_INLINE_TRACE_AFTER_DISPATCH() {
-    visitor->trace(children_);
-    NGPhysicalFragmentBase::traceAfterDispatch(visitor);
-  }
-
  private:
-  HeapVector<Member<const NGPhysicalFragmentBase>> children_;
+  Vector<const NGPhysicalFragmentBase*> children_;
 };
 
 }  // namespace blink
 
 #endif  // NGPhysicalFragment_h