[LayoutNG] A different approach to multi-col.

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 d2962edc0d73796563384574b7fe9ea6cdbc18ac..fcc1246a0b48a318a7352c8280609cdca0e19792 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_layout_child_iterator.h"
 #include "core/layout/ng/ng_block_node.h"
 #include "core/layout/ng/ng_break_token.h"
 #include "core/layout/ng/ng_column_mapper.h"
@@ -34,11 +35,9 @@ class CORE_EXPORT NGBlockLayoutAlgorithm : public NGLayoutAlgorithm {
   //                    method to access all the children.
   // @param space The constraint space which the algorithm should generate a
   //              fragment within.
-  NGBlockLayoutAlgorithm(LayoutObject* layout_object,
-                         PassRefPtr<const ComputedStyle> style,
-                         NGLayoutInputNode* first_child,
+  NGBlockLayoutAlgorithm(NGBlockNode* node,
                          NGConstraintSpace* space,
-                         NGBreakToken* break_token = nullptr);
+                         NGBlockBreakToken* break_token = nullptr);
 
   Optional<MinAndMaxContentSizes> ComputeMinAndMaxContentSizes() const override;
   RefPtr<NGPhysicalFragment> Layout() override;
@@ -61,42 +60,11 @@ class CORE_EXPORT NGBlockLayoutAlgorithm : public NGLayoutAlgorithm {
   // due to a fragmentainer break.
   bool ProceedToNextUnfinishedSibling(NGPhysicalFragment* child_fragment);
 
-  // Set a break token which contains enough information to be able to resume
-  // layout in the next fragmentainer.
-  void SetPendingBreakToken(NGBlockBreakToken*);
-
-  // Check if we have a pending break token set. Once we have set a pending
-  // break token, we cannot set another one. First we need to abort layout in
-  // the current fragmentainer and resume in the next one.
-  bool HasPendingBreakToken() const;
-
   // Final adjusstments before fragment creation. We need to prevent the
   // fragment from crossing fragmentainer boundaries, and rather create a break
   // token if we're out of space.
   void FinalizeForFragmentation();
 
-  // Return the break token, if any, at which we resumed layout after a
-  // previous break.
-  NGBlockBreakToken* CurrentBlockBreakToken() const;
-
-  // Return the block offset of the previous break, in the fragmented flow
-  // coordinate space, relatively to the start edge of this block.
-  LayoutUnit PreviousBreakOffset() const;
-
-  // Return the offset of the potential next break, in the fragmented flow
-  // coordinate space, relatively to the start edge of this block.
-  LayoutUnit NextBreakOffset() const;
-
-  // Get the amount of block space left in the current fragmentainer for the
-  // child that is about to be laid out.
-  LayoutUnit SpaceAvailableForCurrentChild() const;
-
-  LayoutUnit BorderEdgeForCurrentChild() const {
-    // TODO(mstensho): Need to take care of margin collapsing somehow. We
-    // should at least attempt to estimate what the top margin is going to be.
-    return content_size_;
-  }
-
   // Calculates logical offset for the current fragment using either
   // {@code content_size_} when the fragment doesn't know it's offset
   // or {@code known_fragment_offset} if the fragment knows it's offset
@@ -130,17 +98,15 @@ class CORE_EXPORT NGBlockLayoutAlgorithm : public NGLayoutAlgorithm {
   Persistent<NGConstraintSpace> constraint_space_;
 
   // The break token from which we are currently resuming layout.
-  Persistent<NGBreakToken> break_token_;
+  Persistent<NGBlockBreakToken> break_token_;
 
   std::unique_ptr<NGFragmentBuilder> builder_;
   Persistent<NGConstraintSpaceBuilder> space_builder_;
   Persistent<NGConstraintSpace> space_for_current_child_;
   Persistent<NGLayoutInputNode> current_child_;
+  Persistent<NGBreakToken> current_child_break_token_;
 
-  // Mapper from the fragmented flow coordinate space coordinates to visual
-  // coordinates. Only set on fragmentation context roots, such as multicol
-  // containers. Keeps track of the current fragmentainer.
-  Persistent<NGColumnMapper> fragmentainer_mapper_;
+  std::unique_ptr<NGBlockLayoutChildIterator> child_iterator_;
 
   NGBoxStrut border_and_padding_;
   LayoutUnit content_size_;