[LayoutNG] Initial NGLayoutOpportunityIterator implementation

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

Index: third_party/WebKit/Source/core/layout/ng/ng_physical_constraint_space.cc
diff --git a/third_party/WebKit/Source/core/layout/ng/ng_physical_constraint_space.cc b/third_party/WebKit/Source/core/layout/ng/ng_physical_constraint_space.cc
index 4172fe64f40f632c65c262ded322899f1cbe0135..b1229424b91ac783c76ecba5a7f27268ec02e871 100644
--- a/third_party/WebKit/Source/core/layout/ng/ng_physical_constraint_space.cc
+++ b/third_party/WebKit/Source/core/layout/ng/ng_physical_constraint_space.cc
@@ -45,11 +45,11 @@ void NGPhysicalConstraintSpace::AddExclusion(const NGExclusion,
   // TODO(layout-ng): Implement.
 }
 
-DoublyLinkedList<const NGExclusion> NGPhysicalConstraintSpace::Exclusions(
-    unsigned options) const {
-  DoublyLinkedList<const NGExclusion> exclusions;
-  // TODO(layout-ng): Implement.
-  return exclusions;
+const DoublyLinkedList<const NGExclusion>*
+NGPhysicalConstraintSpace::Exclusions(unsigned options) const {
+  // TODO(layout-ng): Filter based on options? Perhaps layout Opportunities
+  // should filter instead?
+  return &exclusions_;
 }
 
 }  // namespace blink