1 files changed, 43 insertions, 2 deletions
diff --git a/layout/base/nsDisplayList.h b/layout/base/nsDisplayList.h
index 9431e2cc0..69d13ded9 100644
--- a/layout/base/nsDisplayList.h
+++ b/layout/base/nsDisplayList.h
@@ -2738,7 +2738,8 @@ public:
                                          nsDisplayList* aList,
                                          bool aAllowWillPaintBorderOptimization = true,
                                          nsStyleContext* aStyleContext = nullptr,
-                                         const nsRect& aBackgroundOriginRect = nsRect());
+                                         const nsRect& aBackgroundOriginRect = nsRect(),
+                                         nsIFrame* aSecondaryReferenceFrame = nullptr);
 
   virtual LayerState GetLayerState(nsDisplayListBuilder* aBuilder,
                                    LayerManager* aManager,
@@ -2838,6 +2839,25 @@ protected:
   bool mShouldTreatAsFixed;
 };
 
+enum class TableType : uint8_t {
+  TABLE,
+  TABLE_COL,
+  TABLE_COL_GROUP,
+  TABLE_ROW,
+  TABLE_ROW_GROUP,
+  TABLE_CELL,
+
+  TABLE_TYPE_MAX
+};
+
+enum class TableTypeBits : uint8_t {
+  COUNT = 3
+};
+
+static_assert(
+  static_cast<uint8_t>(TableType::TABLE_TYPE_MAX) < (1 << (static_cast<uint8_t>(TableTypeBits::COUNT) + 1)),
+  "TableType cannot fit with TableTypeBits::COUNT");
+TableType GetTableTypeFromFrame(nsIFrame* aFrame);
 
 /**
  * A display item to paint the native theme background for a frame.
@@ -3736,7 +3756,7 @@ public:
     return mAnimatedGeometryRootForScrollMetadata;
   }
 
-private:
+protected:
   // For background-attachment:fixed
   nsDisplayFixedPosition(nsDisplayListBuilder* aBuilder, nsIFrame* aFrame,
                          nsDisplayList* aList, uint32_t aIndex);
@@ -3747,6 +3767,27 @@ private:
   bool mIsFixedBackground;
 };
 
+class nsDisplayTableFixedPosition : public nsDisplayFixedPosition
+{
+public:
+  static nsDisplayTableFixedPosition* CreateForFixedBackground(nsDisplayListBuilder* aBuilder,
+                                                               nsIFrame* aFrame,
+                                                               nsDisplayBackgroundImage* aImage,
+                                                               uint32_t aIndex,
+                                                               nsIFrame* aAncestorFrame);
+
+  virtual uint32_t GetPerFrameKey() override {
+    return (mIndex << (nsDisplayItem::TYPE_BITS + static_cast<uint8_t>(TableTypeBits::COUNT))) |
+           (static_cast<uint8_t>(mTableType) << nsDisplayItem::TYPE_BITS) |
+           nsDisplayItem::GetPerFrameKey();
+  }
+protected:
+  nsDisplayTableFixedPosition(nsDisplayListBuilder* aBuilder, nsIFrame* aFrame,
+                              nsDisplayList* aList, uint32_t aIndex, nsIFrame* aAncestorFrame);
+
+  TableType mTableType;
+};
+
 /**
  * This creates an empty scrollable layer. It has no child layers.
  * It is used to record the existence of a scrollable frame in the layer