Paint collapsed borders of a table as one display item

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

Index: third_party/WebKit/Source/core/layout/LayoutTableCell.h
diff --git a/third_party/WebKit/Source/core/layout/LayoutTableCell.h b/third_party/WebKit/Source/core/layout/LayoutTableCell.h
index 6ce3209bf396e44e4c80f27cb087251db698acdd..fd4721d8dcd8dac7133cc946e1d15be194702091 100644
--- a/third_party/WebKit/Source/core/layout/LayoutTableCell.h
+++ b/third_party/WebKit/Source/core/layout/LayoutTableCell.h
@@ -185,8 +185,9 @@ class CORE_EXPORT LayoutTableCell final : public LayoutBlockFlow {
   int borderBefore() const override;
   int borderAfter() const override;
 
-  void collectBorderValues(LayoutTable::CollapsedBorderValues&);
-  static void sortBorderValues(LayoutTable::CollapsedBorderValues&);
+  // Returns true if any collapsed borders related to this cell changed.
+  bool collectBorderValues(Vector<CollapsedBorderValue>&);
+  static void sortBorderValues(Vector<CollapsedBorderValue>&);
 
   void layout() override;
 
@@ -286,38 +287,14 @@ class CORE_EXPORT LayoutTableCell final : public LayoutBlockFlow {
   const char* name() const override { return "LayoutTableCell"; }
 
   bool backgroundIsKnownToBeOpaqueInRect(const LayoutRect&) const override;
-  void invalidateDisplayItemClients(PaintInvalidationReason) const override;
-
-  // TODO(wkorman): Consider renaming to more clearly differentiate from
-  // CollapsedBorderValue.
-  class CollapsedBorderValues : public DisplayItemClient {
-   public:
-    CollapsedBorderValues(const LayoutTable&,
-                          const CollapsedBorderValue& startBorder,
-                          const CollapsedBorderValue& endBorder,
-                          const CollapsedBorderValue& beforeBorder,
-                          const CollapsedBorderValue& afterBorder);
-
-    const CollapsedBorderValue& startBorder() const { return m_startBorder; }
-    const CollapsedBorderValue& endBorder() const { return m_endBorder; }
-    const CollapsedBorderValue& beforeBorder() const { return m_beforeBorder; }
-    const CollapsedBorderValue& afterBorder() const { return m_afterBorder; }
-
-    void setCollapsedBorderValues(const CollapsedBorderValues& other);
-
-    // DisplayItemClient methods.
-    String debugName() const;
-    LayoutRect visualRect() const;
-
-   private:
-    const LayoutTable& m_layoutTable;
-    CollapsedBorderValue m_startBorder;
-    CollapsedBorderValue m_endBorder;
-    CollapsedBorderValue m_beforeBorder;
-    CollapsedBorderValue m_afterBorder;
+
+  struct CollapsedBorderValues {
+    CollapsedBorderValue startBorder;
+    CollapsedBorderValue endBorder;
+    CollapsedBorderValue beforeBorder;
+    CollapsedBorderValue afterBorder;
   };
 
-  bool usesTableAsAdditionalDisplayItemClient() const;
   const CollapsedBorderValues* collapsedBorderValues() const {
     return m_collapsedBorderValues.get();
   }
@@ -390,8 +367,8 @@ class CORE_EXPORT LayoutTableCell final : public LayoutBlockFlow {
   // See also https://code.google.com/p/chromium/issues/detail?id=128227 for
   // some history.
   //
-  // Those functions are called when the cache (m_collapsedBorders) is
-  // invalidated on LayoutTable.
+  // Those functions are called before paint invalidation if the collapsed
+  // borders cache is invalidated on LayoutTable.
   CollapsedBorderValue computeCollapsedStartBorder(
       IncludeBorderColorOrNot = IncludeBorderColor) const;
   CollapsedBorderValue computeCollapsedEndBorder(