Make down-conversion explicit from CFX_ByteString to CFX_ByteStringC.

fpdfsdk/fpdfppo.cpp

Index: fpdfsdk/fpdfppo.cpp
diff --git a/fpdfsdk/fpdfppo.cpp b/fpdfsdk/fpdfppo.cpp
index cab2c6c3e07b8e0ace8ae9fd4f8a26b04bf71127..21d8c7d9aeb9526767f2f43ed9d1ae765dc53566 100644
--- a/fpdfsdk/fpdfppo.cpp
+++ b/fpdfsdk/fpdfppo.cpp
@@ -110,9 +110,9 @@ FX_BOOL CPDF_PageOrganizer::ExportPage(CPDF_Document* pSrcPDFDoc,
       const CFX_ByteString& cbSrcKeyStr = it.first;
       CPDF_Object* pObj = it.second;
       if (cbSrcKeyStr.Compare(("Type")) && cbSrcKeyStr.Compare(("Parent"))) {
-        if (pCurPageDict->KeyExist(cbSrcKeyStr))
-          pCurPageDict->RemoveAt(cbSrcKeyStr);
-        pCurPageDict->SetAt(cbSrcKeyStr, pObj->Clone());
+        if (pCurPageDict->KeyExist(cbSrcKeyStr.AsByteStringC()))
+          pCurPageDict->RemoveAt(cbSrcKeyStr.AsByteStringC());
+        pCurPageDict->SetAt(cbSrcKeyStr.AsByteStringC(), pObj->Clone());
       }
     }
 
@@ -229,7 +229,7 @@ FX_BOOL CPDF_PageOrganizer::UpdateReference(CPDF_Object* pObj,
         }
         if (pNextObj) {
           if (!UpdateReference(pNextObj, pDoc, pObjNumberMap))
-            pDict->RemoveAt(key);
+            pDict->RemoveAt(key.AsByteStringC());
         } else {
           return FALSE;
         }