[css-grid] Refactor the extent for baseline alignment computation

third_party/WebKit/Source/core/layout/GridTrackSizingAlgorithm.h

 // Copyright 2017 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 GridTrackSizingAlgorithm_h
 #define GridTrackSizingAlgorithm_h
 
 #include <memory>
 #include "core/layout/LayoutBox.h"
 #include "core/style/GridPositionsResolver.h"
@@ skipping 244 matching lines @@
   virtual void LayoutGridItemForMinSizeComputation(
       LayoutBox&,
       bool override_size_has_changed) const = 0;
 
   LayoutUnit LogicalHeightForChild(LayoutBox&) const;
 
   bool UpdateOverrideContainingBlockContentSizeForChild(
       LayoutBox&,
       GridTrackSizingDirection) const;
   LayoutUnit ComputeTrackBasedSize() const;
+  Optional<LayoutUnit> ExtentForBaselineAlignment(LayoutBox&) const;
+
   GridTrackSizingDirection Direction() const { return algorithm_.direction_; }
   double FindFrUnitSize(const GridSpan& tracks_span,
                         LayoutUnit left_over_space) const;
   void DistributeSpaceToTracks(Vector<GridTrack*>& tracks,
                                LayoutUnit& available_logical_space) const;
   const LayoutGrid* GetLayoutGrid() const { return algorithm_.layout_grid_; }
   Optional<LayoutUnit> AvailableSpace() const {
     return algorithm_.AvailableSpace();
   }
 
@@ skipping 18 matching lines @@
   static GridTrackSizingDirection FlowAwareDirectionForChild(
       const LayoutGrid*,
       const LayoutBox& child,
       GridTrackSizingDirection);
 
   GridTrackSizingAlgorithm& algorithm_;
 };
 }
 
 #endif  // GridTrackSizingAlgorithm_h