[LayoutNG] Switch NGConstraintSpace to being RefCounted.

third_party/WebKit/Source/core/layout/ng/ng_length_utils.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_length_utils.h"
 
 #include "core/layout/ng/ng_constraint_space.h"
 #include "core/layout/ng/ng_constraint_space_builder.h"
 #include "core/layout/ng/ng_fragment.h"
 #include "core/style/ComputedStyle.h"
@@ skipping 174 matching lines @@
 
 MinAndMaxContentSizes ComputeMinAndMaxContentContribution(
     const ComputedStyle& style,
     const WTF::Optional<MinAndMaxContentSizes>& min_and_max) {
   // Synthesize a zero-sized constraint space for passing to
   // ResolveInlineLength.
   NGWritingMode writing_mode = FromPlatformWritingMode(style.getWritingMode());
   NGConstraintSpaceBuilder builder(writing_mode);
   builder.SetInitialContainingBlockSize(
       NGPhysicalSize{LayoutUnit(), LayoutUnit()});
-  NGConstraintSpace* space = builder.ToConstraintSpace(writing_mode);
+  RefPtr<NGConstraintSpace> space = builder.ToConstraintSpace(writing_mode);
 
   MinAndMaxContentSizes computed_sizes;
   Length inline_size = style.logicalWidth();
   if (inline_size.isAuto()) {
     CHECK(min_and_max.has_value());
     NGBoxStrut border_and_padding =
         ComputeBorders(*space, style) + ComputePadding(*space, style);
     computed_sizes.min_content =
         min_and_max->min_content + border_and_padding.InlineSum();
     computed_sizes.max_content =
@@ skipping 214 matching lines @@
                              Optional<LayoutUnit> min,
                              Optional<LayoutUnit> max) {
   if (max && length > max.value())
     length = max.value();
   if (min && length < min.value())
     length = min.value();
   return length;
 }
 
 }  // namespace blink