Make CPDF_Object::GetString() a virtual method.

core/src/fpdfapi/fpdf_parser/fpdf_parser_document.cpp

Index: core/src/fpdfapi/fpdf_parser/fpdf_parser_document.cpp
diff --git a/core/src/fpdfapi/fpdf_parser/fpdf_parser_document.cpp b/core/src/fpdfapi/fpdf_parser/fpdf_parser_document.cpp
index c0f45c5379da63d5fa76af816066b01afef58489..8c2114fb8989e690ee9a09f853f3c57062eb4834 100644
--- a/core/src/fpdfapi/fpdf_parser/fpdf_parser_document.cpp
+++ b/core/src/fpdfapi/fpdf_parser/fpdf_parser_document.cpp
@@ -51,8 +51,8 @@ void CPDF_Document::LoadDoc()
     }
     CPDF_Array* pIDArray = m_pParser->GetIDArray();
     if (pIDArray) {
-        m_ID1 = pIDArray->GetString(0);
-        m_ID2 = pIDArray->GetString(1);
+        m_ID1 = pIDArray->GetStringAt(0);
+        m_ID2 = pIDArray->GetStringAt(1);
     }
     m_PageList.SetSize(_GetPageCount());
 }
@@ -69,8 +69,8 @@ void CPDF_Document::LoadAsynDoc(CPDF_Dictionary *pLinearized)
     m_pInfoDict = indirectObj ? indirectObj->GetDict() : NULL;
     CPDF_Array* pIDArray = m_pParser->GetIDArray();
     if (pIDArray) {
-        m_ID1 = pIDArray->GetString(0);
-        m_ID2 = pIDArray->GetString(1);
+        m_ID1 = pIDArray->GetStringAt(0);
+        m_ID2 = pIDArray->GetStringAt(1);
     }
     FX_DWORD dwPageCount = 0;
     CPDF_Object *pCount = pLinearized->GetElement(FX_BSTRC("N"));
@@ -341,14 +341,14 @@ FX_BOOL CPDF_Document::IsOwner() const
 }
 FX_BOOL CPDF_Document::IsFormStream(FX_DWORD objnum, FX_BOOL& bForm) const
 {
-    {
-        CPDF_Object* pObj;
-        if (m_IndirectObjs.Lookup((void*)(uintptr_t)objnum, (void*&)pObj)) {
-            bForm = pObj->GetType() == PDFOBJ_STREAM &&
-                    ((CPDF_Stream*)pObj)->GetDict()->GetString(FX_BSTRC("Subtype")) == FX_BSTRC("Form");
-            return TRUE;
-        }
+    CPDF_Object* pObj;
+    if (m_IndirectObjs.Lookup((void*)(uintptr_t)objnum, (void*&)pObj)) {
+        bForm =
+            (pObj->GetType() == PDFOBJ_STREAM &&
+             ((CPDF_Stream*)pObj)->GetDict()->GetStringAt("Subtype") == "Form");
+        return TRUE;
     }
+
     if (m_pParser == NULL) {
         bForm = FALSE;
         return TRUE;