[LayoutNG] Switch NGBreakToken to being RefCounted.

third_party/WebKit/Source/core/layout/ng/ng_block_layout_algorithm.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 NGBlockLayoutAlgorithm_h
 #define NGBlockLayoutAlgorithm_h
 
 #include "core/CoreExport.h"
+#include "core/layout/ng/ng_block_break_token.h"
 #include "core/layout/ng/ng_block_node.h"
 #include "core/layout/ng/ng_break_token.h"
 #include "core/layout/ng/ng_fragment_builder.h"
 #include "core/layout/ng/ng_layout_algorithm.h"
 #include "core/layout/ng/ng_units.h"
 #include "wtf/RefPtr.h"
 
 namespace blink {
 
 class ComputedStyle;
 class NGBlockBreakToken;
 class NGConstraintSpace;
 class NGConstraintSpaceBuilder;
 class NGInlineNode;
 class NGLayoutResult;
 
 // A class for general block layout (e.g. a <div> with no special style).
 // Lays out the children in sequence.
 class CORE_EXPORT NGBlockLayoutAlgorithm : public NGLayoutAlgorithm {
  public:
   // Default constructor.
   // @param node The input node to perform layout upon.
   // @param space The constraint space which the algorithm should generate a
   //              fragment within.
   // @param break_token The break token from which the layout should start.
   NGBlockLayoutAlgorithm(NGBlockNode* node,
                          NGConstraintSpace* space,
-                         NGBlockBreakToken* break_token = nullptr);
+                         RefPtr<NGBlockBreakToken> break_token = nullptr);
 
   Optional<MinAndMaxContentSizes> ComputeMinAndMaxContentSizes() const override;
   RefPtr<NGLayoutResult> Layout() override;
 
  private:
   NGBoxStrut CalculateMargins(const NGConstraintSpace& space,
                               const ComputedStyle& style);
 
   // Creates a new constraint space for the current child.
   NGConstraintSpace* CreateConstraintSpaceForCurrentChild();
@@ skipping 34 matching lines @@
   const NGConstraintSpace& CurrentChildConstraintSpace() const {
     return *space_for_current_child_.get();
   }
 
   const ComputedStyle& Style() const { return node_->Style(); }
 
   Persistent<NGBlockNode> node_;
   Persistent<NGConstraintSpace> constraint_space_;
 
   // The break token from which we are currently resuming layout.
-  Persistent<NGBlockBreakToken> break_token_;
+  RefPtr<NGBlockBreakToken> break_token_;

[ikilpatrick, 2017/02/28 17:13:13]

I could also make this a raw ptr? (and other alg. classes).

 
   std::unique_ptr<NGFragmentBuilder> builder_;
   Persistent<NGConstraintSpaceBuilder> space_builder_;
   Persistent<NGConstraintSpace> space_for_current_child_;
   Persistent<NGLayoutInputNode> current_child_;
 
   NGBoxStrut border_and_padding_;
   LayoutUnit content_size_;
   LayoutUnit max_inline_size_;
   // MarginStrut for the previous child.
   NGMarginStrut curr_margin_strut_;
   NGLogicalOffset bfc_offset_;
   NGLogicalOffset curr_bfc_offset_;
   NGBoxStrut curr_child_margins_;
 };
 
 }  // namespace blink
 
 #endif  // NGBlockLayoutAlgorithm_h