[LayoutNG] Switch NGBreakToken to being RefCounted.

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

Index: third_party/WebKit/Source/core/layout/ng/ng_block_layout_algorithm.h
diff --git a/third_party/WebKit/Source/core/layout/ng/ng_block_layout_algorithm.h b/third_party/WebKit/Source/core/layout/ng/ng_block_layout_algorithm.h
index f0d9377e4b8e54835bcb130907b068fa7a3e4c7f..249e3f15c70c9791198a20faf3cfb857899eff5c 100644
--- a/third_party/WebKit/Source/core/layout/ng/ng_block_layout_algorithm.h
+++ b/third_party/WebKit/Source/core/layout/ng/ng_block_layout_algorithm.h
@@ -6,6 +6,7 @@
 #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"
@@ -33,7 +34,7 @@ class CORE_EXPORT NGBlockLayoutAlgorithm : public NGLayoutAlgorithm {
   // @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;
@@ -88,7 +89,7 @@ class CORE_EXPORT NGBlockLayoutAlgorithm : public NGLayoutAlgorithm {
   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_;