[LayoutNG] A different approach to multi-col.

third_party/WebKit/Source/core/layout/ng/ng_block_node.cc

Index: third_party/WebKit/Source/core/layout/ng/ng_block_node.cc
diff --git a/third_party/WebKit/Source/core/layout/ng/ng_block_node.cc b/third_party/WebKit/Source/core/layout/ng/ng_block_node.cc
index f95e7fd31ac1655e8a3f8eccaaf4d1fa963924e2..fa37f4ba1d9ca781040a12708b4438e48960a572 100644
--- a/third_party/WebKit/Source/core/layout/ng/ng_block_node.cc
+++ b/third_party/WebKit/Source/core/layout/ng/ng_block_node.cc
@@ -15,6 +15,7 @@
 #include "core/layout/ng/ng_fragment_builder.h"
 #include "core/layout/ng/ng_inline_node.h"
 #include "core/layout/ng/ng_length_utils.h"
+#include "core/layout/ng/ng_multi_column_layout_algorithm.h"
 #include "core/layout/ng/ng_writing_mode.h"
 #include "core/paint/PaintLayer.h"
 #include "platform/RuntimeEnabledFeatures.h"
@@ -85,10 +86,17 @@ RefPtr<NGPhysicalFragment> NGBlockNode::Layout(
     return fragment_;
   }
 
-  RefPtr<NGPhysicalFragment> fragment =
-      NGBlockLayoutAlgorithm(GetLayoutObject(), &Style(), FirstChild(),
-                             constraint_space, CurrentBreakToken())
-          .Layout();
+  RefPtr<NGPhysicalFragment> fragment = nullptr;
+  if (Style().specifiesColumns()) {
+    fragment =
+        NGMultiColumnLayoutAlgorithm(this, constraint_space,
+                                     toNGBlockBreakToken(CurrentBreakToken()))
+            .Layout();
+  } else {
+    fragment = NGBlockLayoutAlgorithm(this, constraint_space,
+                                      toNGBlockBreakToken(CurrentBreakToken()))
+                   .Layout();
+  }
 
   fragment_ = toNGPhysicalBoxFragment(fragment.get());
   CopyFragmentDataToLayoutBox(*constraint_space);
@@ -121,8 +129,7 @@ MinAndMaxContentSizes NGBlockNode::ComputeMinAndMaxContentSizes() {
           .ToConstraintSpace();
 
   // TODO(cbiesinger): For orthogonal children, we need to always synthesize.
-  NGBlockLayoutAlgorithm minmax_algorithm(layout_box_, &Style(), FirstChild(),
-                                          constraint_space);
+  NGBlockLayoutAlgorithm minmax_algorithm(this, constraint_space);
   Optional<MinAndMaxContentSizes> maybe_sizes =
       minmax_algorithm.ComputeMinAndMaxContentSizes();
   if (maybe_sizes.has_value())
@@ -305,7 +312,7 @@ RefPtr<NGPhysicalBoxFragment> NGBlockNode::RunOldLayout(
   LayoutRect overflow = layout_box_->layoutOverflowRect();
   // TODO(layout-ng): This does not handle writing modes correctly (for
   // overflow)
-  NGFragmentBuilder builder(NGPhysicalFragment::kFragmentBox, layout_box_);
+  NGFragmentBuilder builder(NGPhysicalFragment::kFragmentBox, this);
   builder.SetInlineSize(layout_box_->logicalWidth())
       .SetBlockSize(layout_box_->logicalHeight())
       .SetDirection(layout_box_->styleRef().direction())