Fix paint invalidation rects for repeating paginated table headers.

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 407c56fca2ded2dd62a4a5a4a208d9a46a630fea..0ae4fb46923ad596b573577cd6a435dc06ebf617 100644
--- a/third_party/WebKit/Source/core/layout/LayoutTableSection.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutTableSection.cpp
@@ -1690,4 +1690,30 @@ void LayoutTableSection::setLogicalPositionForCell(LayoutTableCell* cell, unsign
     cell->setLogicalLocation(cellLocation);
 }
 
+bool LayoutTableSection::hasRepeatingHeaderGroup() const
+{
+    if (getPaginationBreakability() == LayoutBox::AllowAnyBreaks)
+        return false;
+    // TODO(rhogan): Should we paint a header repeatedly if it's self-painting?
+    if (hasSelfPaintingLayer())
+        return false;
+    LayoutUnit pageHeight = table()->pageLogicalHeightForOffset(LayoutUnit());
+    if (!pageHeight)
+        return false;
+    return true;
+}
+
+bool LayoutTableSection::mapToVisualRectInAncestorSpace(const LayoutBoxModelObject* ancestor, LayoutRect& rect, VisualRectFlags flags) const
+{
+    if (ancestor == this)
+        return true;
+    // Repeating table headers are painted once per fragmentation page/column. This does not go through the regular fragmentation machinery,
+    // so we need special code to expand the invalidation rect to contain all positions of the header in all columns.
+    // Note that this is in flow thread coordinates, not visual coordinates. The enclosing LayoutFlowThread will convert to visual coordinates.
+    if (table()->header() == this && hasRepeatingHeaderGroup())
+        rect.setHeight(table()->logicalHeight());
+    return LayoutTableBoxComponent::mapToVisualRectInAncestorSpace(ancestor, rect, flags);
+}
+
+
 } // namespace blink