Paint backgrounds of a table section/row in one display item

third_party/WebKit/Source/core/paint/TablePaintInvalidator.cpp

Index: third_party/WebKit/Source/core/paint/TablePaintInvalidator.cpp
diff --git a/third_party/WebKit/Source/core/paint/TablePaintInvalidator.cpp b/third_party/WebKit/Source/core/paint/TablePaintInvalidator.cpp
index f76452aa5ec361e5e0a9ec28ca27b3c851cfdbd1..01897fa73fbcd6d1541e89eb4b99f5cf5932d545 100644
--- a/third_party/WebKit/Source/core/paint/TablePaintInvalidator.cpp
+++ b/third_party/WebKit/Source/core/paint/TablePaintInvalidator.cpp
@@ -18,81 +18,37 @@ PaintInvalidationReason TablePaintInvalidator::invalidatePaintIfNeeded() {
   PaintInvalidationReason reason =
       BoxPaintInvalidator(m_table, m_context).invalidatePaintIfNeeded();
 
-  // Table cells paint background from the containing column group, column,
-  // section and row.  If background of any of them changed, we need to
-  // invalidate all affected cells.  Here use shouldDoFullPaintInvalidation() as
-  // a broader condition of background change.
-
-  // If any col changed background, we'll check all cells for background
-  // changes.
+  // If any col changed background, we need to invalidate all sections because
+  // col background paints into section's background display item.
   bool hasColChangedBackground = false;
-  bool visualRectChanged = m_context.oldVisualRect != m_table.visualRect();
-  for (LayoutTableCol* col = m_table.firstColumn(); col;
-       col = col->nextColumn()) {
-    // LayoutTableCol uses the table's localVisualRect(). Should check column
-    // for paint invalidation when table's visual rect changed.
-    if (visualRectChanged)
-      col->setMayNeedPaintInvalidation();
-    // This ensures that the backgroundChangedSinceLastPaintInvalidation flag
-    // is up-to-date.
-    col->ensureIsReadyForPaintInvalidation();
-    if (col->backgroundChangedSinceLastPaintInvalidation()) {
-      hasColChangedBackground = true;
-      break;
+  if (m_table.hasColElements()) {
+    bool visualRectChanged = m_context.oldVisualRect != m_table.visualRect();
+    for (LayoutTableCol* col = m_table.firstColumn(); col;
+         col = col->nextColumn()) {
+      // LayoutTableCol uses the table's localVisualRect(). Should check column
+      // for paint invalidation when table's visual rect changed.
+      if (visualRectChanged)
+        col->setMayNeedPaintInvalidation();
+      // This ensures that the backgroundChangedSinceLastPaintInvalidation flag
+      // is up-to-date.
+      col->ensureIsReadyForPaintInvalidation();
+      if (col->backgroundChangedSinceLastPaintInvalidation()) {
+        hasColChangedBackground = true;
+        break;
+      }
     }
   }
-  for (LayoutObject* child = m_table.firstChild(); child;
-       child = child->nextSibling()) {
-    if (!child->isTableSection())
-      continue;
-    LayoutTableSection* section = toLayoutTableSection(child);
-    section->ensureIsReadyForPaintInvalidation();
-    ObjectPaintInvalidator sectionInvalidator(*section);
-    if (!hasColChangedBackground && !section->shouldCheckForPaintInvalidation())
-      continue;
-    for (LayoutTableRow* row = section->firstRow(); row; row = row->nextRow()) {
-      row->ensureIsReadyForPaintInvalidation();
-      if (!hasColChangedBackground &&
-          !section->backgroundChangedSinceLastPaintInvalidation() &&
-          !row->backgroundChangedSinceLastPaintInvalidation())
+
+  if (hasColChangedBackground) {
+    for (LayoutObject* child = m_table.firstChild(); child;
+         child = child->nextSibling()) {
+      if (!child->isTableSection())
         continue;
-      for (LayoutTableCell* cell = row->firstCell(); cell;
-           cell = cell->nextCell()) {
-        cell->ensureIsReadyForPaintInvalidation();
-        bool invalidated = false;
-        // Table cells paint container's background on the container's backing
-        // instead of its own (if any), so we must invalidate it by the
-        // containers.
-        if (section->backgroundChangedSinceLastPaintInvalidation()) {
-          sectionInvalidator
-              .slowSetPaintingLayerNeedsRepaintAndInvalidateDisplayItemClient(
-                  cell->backgroundDisplayItemClient(),
-                  PaintInvalidationStyleChange);
-          invalidated = true;
-        } else if (hasColChangedBackground) {
-          LayoutTable::ColAndColGroup colAndColGroup =
-              m_table.colElementAtAbsoluteColumn(cell->absoluteColumnIndex());
-          LayoutTableCol* column = colAndColGroup.col;
-          LayoutTableCol* columnGroup = colAndColGroup.colgroup;
-          if ((columnGroup &&
-               columnGroup->backgroundChangedSinceLastPaintInvalidation()) ||
-              (column &&
-               column->backgroundChangedSinceLastPaintInvalidation())) {
-            sectionInvalidator
-                .slowSetPaintingLayerNeedsRepaintAndInvalidateDisplayItemClient(
-                    cell->backgroundDisplayItemClient(),
-                    PaintInvalidationStyleChange);
-            invalidated = true;
-          }
-        }
-        if ((!invalidated || row->hasSelfPaintingLayer()) &&
-            row->backgroundChangedSinceLastPaintInvalidation()) {
-          ObjectPaintInvalidator(*row)
-              .slowSetPaintingLayerNeedsRepaintAndInvalidateDisplayItemClient(
-                  cell->backgroundDisplayItemClient(),
-                  PaintInvalidationStyleChange);
-        }
-      }
+      LayoutTableSection* section = toLayoutTableSection(child);
+      section->ensureIsReadyForPaintInvalidation();
+      ObjectPaintInvalidator(*section)
+          .slowSetPaintingLayerNeedsRepaintAndInvalidateDisplayItemClient(
+              *section, PaintInvalidationStyleChange);
     }
   }