[LayoutNG] Initial NGLayoutOpportunityIterator implementation

third_party/WebKit/Source/core/layout/ng/ng_constraint_space.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 NGConstraintSpace_h
 #define NGConstraintSpace_h
 
 #include "core/CoreExport.h"
 #include "core/layout/ng/ng_physical_constraint_space.h"
 #include "core/layout/ng/ng_writing_mode.h"
@@ skipping 94 matching lines @@
 class CORE_EXPORT NGLayoutOpportunityIterator final {
  public:
   NGLayoutOpportunityIterator(NGConstraintSpace* space,
                               unsigned clear,
                               bool for_inline_or_bfc)
       : constraint_space_(space),
         clear_(clear),
         for_inline_or_bfc_(for_inline_or_bfc) {}
   ~NGLayoutOpportunityIterator() {}
 
-  const NGDerivedConstraintSpace* Next();
+  NGConstraintSpace* Next();
 
  private:
   Persistent<NGConstraintSpace> constraint_space_;
   unsigned clear_;
   bool for_inline_or_bfc_;
 };
 
 }  // namespace blink
 
 #endif  // NGConstraintSpace_h