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

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 ae42aec7653bb485b37f094488470f9829c2f779..d6c6df4d4954fcd76652bd3f0e02685ebb4bfad1 100644
--- a/third_party/WebKit/Source/core/paint/TablePaintInvalidator.cpp
+++ b/third_party/WebKit/Source/core/paint/TablePaintInvalidator.cpp
@@ -23,6 +23,19 @@ PaintInvalidationReason TablePaintInvalidator::invalidatePaintIfNeeded() {
   // invalidate all affected cells.  Here use shouldDoFullPaintInvalidation() as
   // a broader condition of background change.
 
+  // Note there are explicit calls to

[wkorman, 2016/11/15 01:05:33]

This documents the explicit calls to create the clients noted below, if you've
an alternate preference for how to structure in light of my note on const-ness
and Painter, let me know.

+  // LayoutTableCell::createCompositedCellDisplayItemClients() for all
+  // composited table cell cases below so as to only lazily create the special
+  // display item clients. Composited table cells are an uncommon case. The
+  // logic below handles the case where a cell's row, column, column group, or
+  // section style changes and it moves to a new state where it does not require
+  // these clients.
+  //
+  // We could move the lazy client creation to the specific accessor methods in
+  // LayoutTableCell, but those are const, TableCellPainter's LayoutTableCell is
+  // also const, and TableCellPainter uses those same client accessor methods,
+  // which would fail const-ness.

[Xianzhu, 2016/11/15 02:58:23]

We can use mutable keyword or the LayoutObject::getMutableForPainting() pattern.
We do need and allow some part of layout objects to be mutable for painting
code, but are using const to avoid unintended mutations. 

+
   // If any col changed background, we'll check all cells for background
   // changes.
   bool hasColChangedBackground = false;
@@ -58,27 +71,57 @@ PaintInvalidationReason TablePaintInvalidator::invalidatePaintIfNeeded() {
           sectionInvalidator
               .slowSetPaintingLayerNeedsRepaintAndInvalidateDisplayItemClient(
                   *cell, PaintInvalidationStyleChange);
+          if (cell->usesCompositedCellDisplayItemClients()) {
+            cell->createCompositedCellDisplayItemClients();
+            sectionInvalidator.invalidateDisplayItemClient(
+                *cell->sectionBackgroundDisplayItemClient(),
+                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())) {
+          bool colGroupBackgroundChanged =
+              columnGroup &&
+              columnGroup->backgroundChangedSinceLastPaintInvalidation();
+          bool colBackgroundChanged =
+              column && column->backgroundChangedSinceLastPaintInvalidation();
+          if (colGroupBackgroundChanged || colBackgroundChanged) {
             sectionInvalidator
                 .slowSetPaintingLayerNeedsRepaintAndInvalidateDisplayItemClient(
                     *cell, PaintInvalidationStyleChange);
+            if (colBackgroundChanged &&
+                cell->usesCompositedCellDisplayItemClients()) {
+              cell->createCompositedCellDisplayItemClients();
+              sectionInvalidator.invalidateDisplayItemClient(
+                  *cell->colBackgroundDisplayItemClient(),
+                  PaintInvalidationStyleChange);
+            }
+            if (colGroupBackgroundChanged &&
+                cell->usesCompositedCellDisplayItemClients()) {
+              cell->createCompositedCellDisplayItemClients();
+              sectionInvalidator.invalidateDisplayItemClient(
+                  *cell->colGroupBackgroundDisplayItemClient(),
+                  PaintInvalidationStyleChange);
+            }
             invalidated = true;
           }
         }
         if ((!invalidated || row->hasSelfPaintingLayer()) &&
-            row->backgroundChangedSinceLastPaintInvalidation())
-          ObjectPaintInvalidator(*row)
+            row->backgroundChangedSinceLastPaintInvalidation()) {
+          ObjectPaintInvalidator invalidator = ObjectPaintInvalidator(*row);
+          invalidator
               .slowSetPaintingLayerNeedsRepaintAndInvalidateDisplayItemClient(
                   *cell, PaintInvalidationStyleChange);
+          if (cell->usesCompositedCellDisplayItemClients()) {
+            cell->createCompositedCellDisplayItemClients();
+            invalidator.invalidateDisplayItemClient(
+                *cell->rowBackgroundDisplayItemClient(),
+                PaintInvalidationStyleChange);
+          }
+        }
       }
     }
   }