Display table header groups at the top of each page

third_party/WebKit/Source/core/layout/LayoutTableSection.cpp

Index: third_party/WebKit/Source/core/layout/LayoutTableSection.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutTableSection.cpp b/third_party/WebKit/Source/core/layout/LayoutTableSection.cpp
index 7ed46e8678ee4fb93309222f4e8ffb0423031181..f1808351efcc619b984ebfe727f37585231b76e7 100644
--- a/third_party/WebKit/Source/core/layout/LayoutTableSection.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutTableSection.cpp
@@ -972,6 +972,11 @@ void LayoutTableSection::layoutRows()
             if (isPaginated) {
                 paginationStrutOnRow = paginationStrutForRow(rowLayoutObject, LayoutUnit(m_rowPos[r]));
                 if (paginationStrutOnRow) {
+                    LayoutTableSection* header = table()->header();
+                    // If we have a header group we will paint it at the top of each page, move the rows
+                    // down to accomodate it.
+                    if (header && header != this)
+                        paginationStrutOnRow += header->logicalHeight().toInt();
                     for (unsigned rowIndex = r; rowIndex <= totalRows; rowIndex++)
                         m_rowPos[rowIndex] += paginationStrutOnRow;
                 }
@@ -1099,7 +1104,10 @@ void LayoutTableSection::layoutRows()
 
 int LayoutTableSection::paginationStrutForRow(LayoutTableRow* row, LayoutUnit logicalOffset) const
 {
-    if (row->getPaginationBreakability() == AllowAnyBreaks)
+    // Even if the row allows us to break-inside, we will want to put a strut on the row if we have a header
+    // group that wants to appear at the top of each page.
+    bool tableHeaderForcesStrut = table()->header() ? table()->header()->getPaginationBreakability() != AllowAnyBreaks : false;
+    if (row->getPaginationBreakability() == AllowAnyBreaks && !tableHeaderForcesStrut)
         return 0;
     LayoutUnit pageLogicalHeight = pageLogicalHeightForOffset(logicalOffset);
     if (!pageLogicalHeight)