[LayoutNG] Switch NGConstraintSpace to being RefCounted.

third_party/WebKit/Source/core/layout/ng/ng_constraint_space.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_constraint_space.h"
 
 #include "core/layout/LayoutBlock.h"
 #include "core/layout/LayoutView.h"
 #include "core/layout/ng/ng_constraint_space_builder.h"
 #include "core/layout/ng/ng_layout_opportunity_iterator.h"
@@ skipping 33 matching lines @@
       block_direction_fragmentation_type_(block_direction_fragmentation_type),
       is_new_fc_(is_new_fc),
       is_anonymous_(is_anonymous),
       writing_mode_(writing_mode),
       direction_(static_cast<unsigned>(direction)),
       margin_strut_(margin_strut),
       bfc_offset_(bfc_offset),
       exclusions_(exclusions),
       clearance_offset_(clearance_offset) {}
 
-NGConstraintSpace* NGConstraintSpace::CreateFromLayoutObject(
+RefPtr<NGConstraintSpace> NGConstraintSpace::CreateFromLayoutObject(
     const LayoutBox& box) {
   auto writing_mode = FromPlatformWritingMode(box.styleRef().getWritingMode());
   bool parallel_containing_block = IsParallelWritingMode(
       FromPlatformWritingMode(
           box.containingBlock()->styleRef().getWritingMode()),
       writing_mode);
   bool fixed_inline = false, fixed_block = false;
 
   LayoutUnit available_logical_width;
   if (parallel_containing_block)
@@ skipping 79 matching lines @@
       bfc_offset_.block_offset.toString().ascii().data(),
       AvailableSize().inline_size.toString().ascii().data(),
       AvailableSize().block_size.toString().ascii().data(),
       margin_strut_.ToString().ascii().data(),
       clearance_offset_.has_value()
           ? clearance_offset_.value().toString().ascii().data()
           : "none");
 }
 
 }  // namespace blink