Remove "this==NULL" and adjust corresponding callers

core/src/fpdfdoc/doc_annot.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 "../../include/fpdfdoc/fpdf_doc.h"
 #include "../../include/fpdfapi/fpdf_pageobj.h"
 CPDF_AnnotList::CPDF_AnnotList(CPDF_Page* pPage)
 {
@@ skipping 147 matching lines @@
     while (pos) {
         void* pForm;
         void* pObjects;
         m_APMap.GetNextAssoc(pos, pForm, pObjects);
         delete (CPDF_PageObjects*)pObjects;
     }
     m_APMap.RemoveAll();
 }
 CFX_ByteString CPDF_Annot::GetSubType() const
 {
-    return m_pAnnotDict->GetConstString(FX_BSTRC("Subtype"));
+    return m_pAnnotDict ? m_pAnnotDict->GetConstString(FX_BSTRC("Subtype")) : CFX_ByteStringC();
 }
 void CPDF_Annot::GetRect(CPDF_Rect& rect) const
 {
     if (m_pAnnotDict == NULL) {
         return;
     }
     rect = m_pAnnotDict->GetRect("Rect");
     rect.Normalize();
 }
 CPDF_Stream* FPDFDOC_GetAnnotAP(CPDF_Dictionary* pAnnotDict, CPDF_Annot::AppearanceMode mode)
@@ skipping 16 matching lines @@
         return NULL;
     }
     CPDF_Stream* pStream = NULL;
     if (psub->GetType() == PDFOBJ_STREAM) {
         pStream = (CPDF_Stream*)psub;
     } else if (psub->GetType() == PDFOBJ_DICTIONARY) {
         CFX_ByteString as = pAnnotDict->GetString("AS");
         if (as.IsEmpty()) {
             CFX_ByteString value = pAnnotDict->GetString(FX_BSTRC("V"));
             if (value.IsEmpty()) {
-                value = pAnnotDict->GetDict(FX_BSTRC("Parent"))->GetString(FX_BSTRC("V"));
+                CPDF_Dictionary* pDict = pAnnotDict->GetDict(FX_BSTRC("Parent"));
+                value = pDict ? pDict->GetString(FX_BSTRC("V")) : CFX_ByteString();
             }
             if (value.IsEmpty() || !((CPDF_Dictionary*)psub)->KeyExist(value)) {
                 as = FX_BSTRC("Off");
             } else {
                 as = value;
             }
         }
         pStream = ((CPDF_Dictionary*)psub)->GetStream(as);
     }
     return pStream;
@@ skipping 294 matching lines @@
         if (pIRT != m_pAnnotDict) {
             continue;
         }
         if (count == index) {
             return pAnnot;
         }
         count ++;
     }
     return NULL;
 }