[TablesNG] Make LayoutCaption NG compatible

LayoutNGCaptions can be created in both Legacy and NG tables.
Only Legacy tables require AddCaption/RemoveCaption calls.

Bug: 958381
Change-Id: I43131f66b794dc43bea41d6b39fdf66eac72aa86
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2363556
Commit-Queue: Aleks Totic <atotic@chromium.org>
Reviewed-by: Morten Stenshorne <mstensho@chromium.org>
Cr-Commit-Position: refs/heads/master@{#799824}

third_party/blink/renderer/core/layout/ng/table/layout_ng_table_caption.cc

@@ -5,6 +5,7 @@
 #include "third_party/blink/renderer/core/layout/ng/table/layout_ng_table_caption.h"
 
 #include "third_party/blink/renderer/core/layout/layout_analyzer.h"
+#include "third_party/blink/renderer/core/layout/layout_table.h"
 #include "third_party/blink/renderer/core/layout/layout_view.h"
 #include "third_party/blink/renderer/core/layout/ng/ng_block_node.h"
 #include "third_party/blink/renderer/core/layout/ng/ng_box_fragment.h"
@@ -53,6 +54,24 @@ void LayoutNGTableCaption::CalculateAndSetMargins(
                                         containing_block_style.Direction()));
 }
 
+void LayoutNGTableCaption::InsertedIntoTree() {
+  LayoutBlockFlow::InsertedIntoTree();
+
+  LayoutNGTableInterface* table_interface = TableInterface();
+  if (!table_interface->ToLayoutObject()->IsLayoutNGMixin())
+    To<LayoutTable>(table_interface->ToMutableLayoutObject())->AddCaption(this);
+}
+
+void LayoutNGTableCaption::WillBeRemovedFromTree() {
+  LayoutBlockFlow::WillBeRemovedFromTree();
+
+  LayoutNGTableInterface* table_interface = TableInterface();
+  if (!table_interface->ToLayoutObject()->IsLayoutNGMixin()) {
+    To<LayoutTable>(table_interface->ToMutableLayoutObject())
+        ->RemoveCaption(this);
+  }
+}
+
 void LayoutNGTableCaption::UpdateBlockLayout(bool relayout_children) {
   LayoutAnalyzer::BlockScope analyzer(*this);
 
@@ -73,4 +92,8 @@ void LayoutNGTableCaption::UpdateBlockLayout(bool relayout_children) {
          "table algorithm doesn't exist yet!";
 }
 
+LayoutNGTableInterface* LayoutNGTableCaption::TableInterface() const {
+  return ToInterface<LayoutNGTableInterface>(Parent());
+}
+
 }  // namespace blink

third_party/blink/renderer/core/layout/ng/table/layout_ng_table_caption.h

@@ -11,6 +11,8 @@
 
 namespace blink {
 
+class LayoutNGTableInterface;
+
 class CORE_EXPORT LayoutNGTableCaption final
     : public LayoutNGBlockFlowMixin<LayoutTableCaption> {
  public:
@@ -21,8 +23,15 @@ class CORE_EXPORT LayoutNGTableCaption final
   const char* GetName() const override { return "LayoutNGTableCaption"; }
 
  private:
+  // Legacy-only API.
+  void InsertedIntoTree() override;
+  // Legacy-only API.
+  void WillBeRemovedFromTree() override;
+  // Legacy-only API.
   void CalculateAndSetMargins(const NGConstraintSpace&,
                               const NGPhysicalFragment&);
+
+  LayoutNGTableInterface* TableInterface() const;
 };
 
 // wtf/casting.h helper.