Use appropriate background object visual rect for composited table cell backgrounds.

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

Index: third_party/WebKit/Source/core/layout/LayoutTableCell.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutTableCell.cpp b/third_party/WebKit/Source/core/layout/LayoutTableCell.cpp
index 75f5a01f2d23ddc9e31375b6f55e827be82b1a07..25922550148d51c135e0472a834c776347568204 100644
--- a/third_party/WebKit/Source/core/layout/LayoutTableCell.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutTableCell.cpp
@@ -46,7 +46,8 @@ using namespace HTMLNames;
 struct SameSizeAsLayoutTableCell : public LayoutBlockFlow {
   unsigned bitfields;
   int paddings[2];
-  void* pointer;
+  void* pointer1;
+  void* pointer2;
 };
 
 static_assert(sizeof(LayoutTableCell) == sizeof(SameSizeAsLayoutTableCell),
@@ -463,6 +464,15 @@ int LayoutTableCell::cellBaselinePosition() const {
   return (borderBefore() + paddingBefore() + contentLogicalHeight()).toInt();
 }
 
+void LayoutTableCell::ensureIsReadyForPaintInvalidation() {
+  if (!m_rowBackgroundDisplayItemClient &&
+      usesCompositedCellDisplayItemClients()) {
+    m_rowBackgroundDisplayItemClient =
+        wrapUnique(new LayoutTableCell::RowBackgroundDisplayItemClient(*row()));
+  }
+  LayoutBlockFlow::ensureIsReadyForPaintInvalidation();
+}
+
 void LayoutTableCell::styleDidChange(StyleDifference diff,
                                      const ComputedStyle* oldStyle) {
   DCHECK_EQ(style()->display(), EDisplay::TableCell);
@@ -1422,19 +1432,41 @@ bool LayoutTableCell::backgroundIsKnownToBeOpaqueInRect(
   return LayoutBlockFlow::backgroundIsKnownToBeOpaqueInRect(localRect);
 }
 
-bool LayoutTableCell::usesTableAsAdditionalDisplayItemClient() const {
-  // In certain cases such as collapsed borders for composited table cells we
-  // paint content for the cell into the table graphics layer backing and so
-  // must use the table's visual rect.
+LayoutTableCell::RowBackgroundDisplayItemClient::RowBackgroundDisplayItemClient(
+    const LayoutTableRow& layoutTableRow)
+    : m_layoutTableRow(layoutTableRow) {}
+
+String LayoutTableCell::RowBackgroundDisplayItemClient::debugName() const {
+  return "RowBackground";
+}
+
+LayoutRect LayoutTableCell::RowBackgroundDisplayItemClient::visualRect() const {
+  return m_layoutTableRow.visualRect();
+}
+
+bool LayoutTableCell::usesCompositedCellDisplayItemClients() const {

[wkorman, 2016/11/03 01:41:25]

This is a bit of a misnomer since it's also true for SPv2, not just composited
cells, but I couldn't think of something better and I believe we want to use
this same logic for both the table and row case. 'isCompositedOrSPv2' or similar
just seemed unwieldy.

[Xianzhu, 2016/11/03 03:06:48]

I think this is OK. When we remove non-SPv2 code, we'll remove this function and
always use rowBackgroundDisplayItemClient.

+  // Table cells are painted in two special ways that require the use of custom
+  // display item clients when the cell is composited:
+  //
+  // 1. When painting row background we paint content for the cell into the
+  // table row graphics layer backing and so must use the row's visual rect.
+  //
+  // 2. When painting collapsed borders we paint content for the cell into the
+  // table graphics layer backing and so must use the table's visual rect.
   return (hasLayer() && layer()->compositingState() != NotComposited) ||
          RuntimeEnabledFeatures::slimmingPaintV2Enabled();
 }
 
 void LayoutTableCell::invalidateDisplayItemClients(
     PaintInvalidationReason reason) const {
-  if (m_collapsedBorderValues && usesTableAsAdditionalDisplayItemClient()) {
-    ObjectPaintInvalidator(*this).invalidateDisplayItemClient(
-        *m_collapsedBorderValues, reason);
+  if (usesCompositedCellDisplayItemClients()) {
+    ObjectPaintInvalidator invalidator(*this);
+    DCHECK(m_rowBackgroundDisplayItemClient);
+    if (m_collapsedBorderValues) {
+      invalidator.invalidateDisplayItemClient(*m_collapsedBorderValues, reason);
+    }
+    invalidator.invalidateDisplayItemClient(*m_rowBackgroundDisplayItemClient,

[wkorman, 2016/11/03 01:41:25]

This wasn't necessary for all tests to pass but I believe we need to do this to
be correct, unless it's sufficient for us to rely on the one explicit
invalidation of this display item client in TablePaintInvalidator?

+                                            reason);
   }
   LayoutBlockFlow::invalidateDisplayItemClients(reason);
 }