Fix stack overflow in object Clone() functions

core/fpdfapi/fpdf_parser/cpdf_object.cpp

Index: core/fpdfapi/fpdf_parser/cpdf_object.cpp
diff --git a/core/fpdfapi/fpdf_parser/cpdf_object.cpp b/core/fpdfapi/fpdf_parser/cpdf_object.cpp
index ec967d10328ef57960c0caf3d2ef5a460b8eb18f..7da12a2b4f20d976d05b63734cd66b1f25276e70 100644
--- a/core/fpdfapi/fpdf_parser/cpdf_object.cpp
+++ b/core/fpdfapi/fpdf_parser/cpdf_object.cpp
@@ -22,6 +22,21 @@ CPDF_Object* CPDF_Object::GetDirect() const {
   return const_cast<CPDF_Object*>(this);
 }
 
+CPDF_Object* CPDF_Object::CloneObjectNonCyclic(bool bDirect) const {
+  std::set<const CPDF_Object*> visited_objs;
+  return CloneNonCyclic(bDirect, &visited_objs);
+}
+
+CPDF_Object* CPDF_Object::CloneDirectObject() const {
+  return CloneObjectNonCyclic(true);
+}
+
+CPDF_Object* CPDF_Object::CloneNonCyclic(
+    bool bDirect,
+    std::set<const CPDF_Object*>* pVisited) const {
+  return Clone();
+}
+
 void CPDF_Object::Release() {
   if (m_ObjNum)
     return;