Use Layout Opportunity Iterator to position new FC blocks.

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

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef NGLayoutOpportunityIterator_h
 #define NGLayoutOpportunityIterator_h
 
 #include "core/CoreExport.h"
 #include "core/layout/ng/ng_exclusion.h"
+#include "core/layout/ng/ng_fragment.h"
 #include "core/layout/ng/ng_layout_opportunity_tree_node.h"
 #include "platform/wtf/Vector.h"
 #include "platform/wtf/text/StringBuilder.h"
 
 namespace blink {
 
 typedef NGLogicalRect NGLayoutOpportunity;
 typedef Vector<NGLayoutOpportunity> NGLayoutOpportunities;
 
+NGLayoutOpportunity FindLayoutOpportunityForFragment(
+    const NGExclusions* exclusions,
+    const NGLogicalSize& size,
+    const NGLogicalOffset& origin_point,
+    const NGBoxStrut& margins,
+    const NGFragment& fragment);
+
 class CORE_EXPORT NGLayoutOpportunityIterator final {
  public:
   // Default constructor.
   //
   // @param exclusions List of exclusions that should be avoided by this
   //                   iterator while generating layout opportunities.
   // @param available_size Available size that represents a rectangle where this
   //                       iterator searches layout opportunities.
   // @param offset Offset used as a default starting point for layout
   //               opportunities.
@@ skipping 28 matching lines @@
 
   NGLayoutOpportunities opportunities_;
   NGLayoutOpportunities::const_iterator opportunity_iter_;
   std::unique_ptr<NGLayoutOpportunityTreeNode> opportunity_tree_root_;
   NGLogicalOffset offset_;
 };
 
 }  // namespace blink
 
 #endif  // NGLayoutOpportunityIterator_h