Use table as display item client for painting composited collapsed table cell borders.

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 57f1089872620997692b0e55e7b3e25404fa6d20..4c80a05160583d18cc544473db677b3e2f3f2349 100644
--- a/third_party/WebKit/Source/core/layout/LayoutTableCell.h
+++ b/third_party/WebKit/Source/core/layout/LayoutTableCell.h
@@ -286,13 +286,38 @@ class CORE_EXPORT LayoutTableCell final : public LayoutBlockFlow {
   const char* name() const override { return "LayoutTableCell"; }
 
   bool backgroundIsKnownToBeOpaqueInRect(const LayoutRect&) const override;
-
-  struct CollapsedBorderValues {
-    CollapsedBorderValue startBorder;
-    CollapsedBorderValue endBorder;
-    CollapsedBorderValue beforeBorder;
-    CollapsedBorderValue afterBorder;
+  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;
   };
+
+  bool usesTableAsDisplayItemClient() const;

[chrishtr, 2016/10/19 01:13:21]

usesTableAsAdditionalDisplayItemClient()

[wkorman, 2016/10/19 23:07:39]

Done.

   const CollapsedBorderValues* collapsedBorderValues() const {
     return m_collapsedBorderValues.get();
   }