Make CPDF_Object::GetString() a virtual method.

fpdfsdk/src/fsdk_mgr.cpp

 // Copyright 2014 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
 #include "../../public/fpdf_ext.h"
 #include "../include/fsdk_define.h"
 #include "../include/fsdk_mgr.h"
 #include "../include/formfiller/FFL_FormFiller.h"
@@ skipping 714 matching lines @@
         {
                 pAnnotHandler->Annot_OnCreate(pSDKAnnot);
 
         }
 
          return pSDKAnnot;
 }
 
 CPDFSDK_Annot* CPDFSDK_PageView::AddAnnot(CPDF_Dictionary * pDict)
 {
-    return pDict ? AddAnnot(pDict->GetString("Subtype"), pDict) : nullptr;
+    return pDict ? AddAnnot(pDict->GetStringAt("Subtype"), pDict) : nullptr;
 }
 
 CPDFSDK_Annot* CPDFSDK_PageView::AddAnnot(const FX_CHAR* lpSubType,CPDF_Dictionary * pDict)
 {
         return NULL;
 }
 
 FX_BOOL  CPDFSDK_PageView::DeleteAnnot(CPDFSDK_Annot* pAnnot)
 {
         return FALSE;
@@ skipping 265 matching lines @@
 
         for(int i=0; i<m_fxAnnotArray.GetSize(); i++)
         {
                 CPDFSDK_Annot* pAnnot = (CPDFSDK_Annot*)m_fxAnnotArray.GetAt(i);
                 if(pAnnot == pFocusAnnot)
                         return pAnnot;
         }
         return NULL;
 }