Combine 2 exclusions in Layout Opportunity Tree if they shadow each other

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

Index: third_party/WebKit/Source/core/layout/ng/ng_layout_opportunity_iterator.cc
diff --git a/third_party/WebKit/Source/core/layout/ng/ng_layout_opportunity_iterator.cc b/third_party/WebKit/Source/core/layout/ng/ng_layout_opportunity_iterator.cc
index f95d51d176ef7445381c363cce38b3fa787a9741..d2956dfc8a04bb1015035ab014ddcd9bc0dc9312 100644
--- a/third_party/WebKit/Source/core/layout/ng/ng_layout_opportunity_iterator.cc
+++ b/third_party/WebKit/Source/core/layout/ng/ng_layout_opportunity_iterator.cc
@@ -28,7 +28,7 @@ void AppendNodeToString(const NGLayoutOpportunityTreeNode* node,
   for (unsigned i = 0; i < indent; i++)
     indent_builder.append("\t");
 
-  if (!node->exclusion)
+  if (node->IsLeafNode())
     return;
 
   string_builder->append(indent_builder.toString());
@@ -160,6 +160,13 @@ NGLayoutOpportunityTreeNode* CreateRightNGLayoutOpportunityTreeNode(
   return nullptr;
 }
 
+void SplitNGLayoutOpportunityTreeNode(const NGLogicalRect& rect,
+                                      NGLayoutOpportunityTreeNode* node) {
+  node->left = CreateLeftNGLayoutOpportunityTreeNode(node, rect);
+  node->right = CreateRightNGLayoutOpportunityTreeNode(node, rect);
+  node->bottom = CreateBottomNGLayoutOpportunityTreeNode(node, rect);
+}
+
 // Gets/Creates the "TOP" positioned constraint space by splitting
 // the parent node with the exclusion.
 //
@@ -197,24 +204,29 @@ void InsertExclusion(NGLayoutOpportunityTreeNode* node,
   if (!exclusion->rect.IsContained(node->opportunity))
     return;
 
-  if (node->exclusion) {
-    InsertExclusion(node->left, exclusion, opportunities);
-    InsertExclusion(node->bottom, exclusion, opportunities);
-    InsertExclusion(node->right, exclusion, opportunities);
+  if (node->exclusions.isEmpty()) {
+    SplitNGLayoutOpportunityTreeNode(exclusion->rect, node);
+
+    NGLayoutOpportunity top_layout_opp =
+        GetTopSpace(node->opportunity, exclusion->rect);
+    if (!top_layout_opp.IsEmpty())
+      opportunities.push_back(top_layout_opp);
+
+    node->exclusions.push_back(exclusion);
+    node->combined_exclusion = WTF::makeUnique<NGExclusion>(*exclusion);
     return;
   }
 
-  // Split the current node.
-  node->left = CreateLeftNGLayoutOpportunityTreeNode(node, exclusion->rect);
-  node->right = CreateRightNGLayoutOpportunityTreeNode(node, exclusion->rect);
-  node->bottom = CreateBottomNGLayoutOpportunityTreeNode(node, exclusion->rect);
-
-  NGLayoutOpportunity top_layout_opp =
-      GetTopSpace(node->opportunity, exclusion->rect);
-  if (!top_layout_opp.IsEmpty())
-    opportunities.push_back(top_layout_opp);
+  DCHECK(!node->exclusions.isEmpty());
 
-  node->exclusion = exclusion;
+  if (node->combined_exclusion->MaybeCombineWith(*exclusion)) {
+    SplitNGLayoutOpportunityTreeNode(node->combined_exclusion->rect, node);
+    node->exclusions.push_back(exclusion);
+  } else {
+    InsertExclusion(node->left, exclusion, opportunities);
+    InsertExclusion(node->bottom, exclusion, opportunities);
+    InsertExclusion(node->right, exclusion, opportunities);
+  }
 }
 
 // Compares exclusions by their top position.