Provide a dedicated getter for the offset to a repeatable THEAD.

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

 /*
  * Copyright (C) 1997 Martin Jones (mjones@kde.org)
  *           (C) 1997 Torben Weis (weis@kde.org)
  *           (C) 1998 Waldo Bastian (bastian@kde.org)
  *           (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003, 2004, 2005, 2006, 2009, 2010 Apple Inc.
  *               All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 396 matching lines @@
 
   const CollapsedBorderValues& collapsedBorders() const {
     ASSERT(m_collapsedBordersValid);
     return m_collapsedBorders;
   }
 
   void subtractCaptionRect(LayoutRect&) const;
 
   bool isLogicalWidthAuto() const;
 
+  // When table headers are repeated, we need to know the offset from the block
+  // start of the fragmentation context to the first occurrence of the table
+  // header.
+  LayoutUnit offsetToFirstRepeatableHeader() const {

[eae, 2016/10/27 17:05:10]

How about blockOffsetToFirstRepeatableHeader to make it clear which direction
the offset is in?

[mstensho (USE GERRIT), 2016/10/27 20:25:47]

Done.

+    return m_offsetToFirstRepeatableHeader;
+  }
+
   const char* name() const override { return "LayoutTable"; }
 
   // Whether a table has opaque foreground depends on many factors, e.g. border
   // spacing, missing cells, etc. For simplicity, just conservatively assume
   // foreground of all tables are not opaque.
   bool foregroundIsKnownToBeOpaqueInRect(const LayoutRect&,
                                          unsigned) const override {
     return false;
   }
 
@@ skipping 130 matching lines @@
       if (m_effectiveColumns[c].span > 1)
         return c;
     }
     return numEffectiveColumns();
   }
 
   short m_hSpacing;
   short m_vSpacing;
   int m_borderStart;
   int m_borderEnd;
+
+  LayoutUnit m_offsetToFirstRepeatableHeader;
 };
 
 inline LayoutTableSection* LayoutTable::topSection() const {
   ASSERT(!needsSectionRecalc());
   if (m_head)
     return m_head;
   if (m_firstBody)
     return m_firstBody;
   return m_foot;
 }
 
 DEFINE_LAYOUT_OBJECT_TYPE_CASTS(LayoutTable, isTable());
 
 }  // namespace blink
 
 #endif  // LayoutTable_h