[WIP][b:eae_mywip_paint] Paint Selection NG.

third_party/WebKit/Source/core/editing/LayoutSelection.h

Index: third_party/WebKit/Source/core/editing/LayoutSelection.h
diff --git a/third_party/WebKit/Source/core/editing/LayoutSelection.h b/third_party/WebKit/Source/core/editing/LayoutSelection.h
index e309c5d33360a5a8dc56b3e11d89a09071ba4000..48b6c83deb7dc39cb080e86371d40dc013abdb49 100644
--- a/third_party/WebKit/Source/core/editing/LayoutSelection.h
+++ b/third_party/WebKit/Source/core/editing/LayoutSelection.h
@@ -103,6 +103,12 @@ class LayoutSelection final : public GarbageCollected<LayoutSelection> {
   void InvalidatePaintForSelection();
 
   void ClearSelection();
+  // TODO(yoichio): Returns pair<Union<NGOffset, DOMOffset>, Union<NGOffset,
+  // DOMOffset>>. Content of the Union is decided by if
+  // paint_range_.Start(End)LayoutObject() is NG or not. LayoutObject painter
+  // calliing this should know if the LayoutObject is NG and
+  // LayoutObject.SelectionState because SelectionStartEnd().first doesn't make
+  // sense for SelectionState::kEnd LayoutObject.
   std::pair<int, int> SelectionStartEnd();
   void OnDocumentShutdown();