Revert "Revert "Add type cast definitions for CPDF_Reference.""

core/include/fpdfapi/fpdf_objects.h

Index: core/include/fpdfapi/fpdf_objects.h
diff --git a/core/include/fpdfapi/fpdf_objects.h b/core/include/fpdfapi/fpdf_objects.h
index 45ca665b99ac50fafe4a00c94b446162cc3be337..419d5fc23e69b12ad7a46a33ba90f57acf2f8dcc 100644
--- a/core/include/fpdfapi/fpdf_objects.h
+++ b/core/include/fpdfapi/fpdf_objects.h
@@ -84,6 +84,7 @@ class CPDF_Object {
   bool IsDictionary() const { return m_Type == PDFOBJ_DICTIONARY; }
   bool IsName() const { return m_Type == PDFOBJ_NAME; }
   bool IsNumber() const { return m_Type == PDFOBJ_NUMBER; }
+  bool IsReference() const { return m_Type == PDFOBJ_REFERENCE; }
   bool IsStream() const { return m_Type == PDFOBJ_STREAM; }
   bool IsString() const { return m_Type == PDFOBJ_STRING; }
 
@@ -102,6 +103,9 @@ class CPDF_Object {
   CPDF_Number* AsNumber();
   const CPDF_Number* AsNumber() const;
 
+  CPDF_Reference* AsReference();
+  const CPDF_Reference* AsReference() const;
+
   CPDF_Stream* AsStream();
   const CPDF_Stream* AsStream() const;
 
@@ -600,6 +604,13 @@ class CPDF_Reference : public CPDF_Object {
   FX_DWORD m_RefObjNum;
   friend class CPDF_Object;
 };
+inline CPDF_Reference* ToReference(CPDF_Object* obj) {
+  return obj ? obj->AsReference() : nullptr;
+}
+inline const CPDF_Reference* ToReference(const CPDF_Object* obj) {
+  return obj ? obj->AsReference() : nullptr;
+}
+
 class CPDF_IndirectObjects {
  public:
   CPDF_IndirectObjects(CPDF_Parser* pParser);