Avoid string allocs for CMap_GetString() return value.

core/fpdfapi/fpdf_font/cpdf_cidfont.cpp

 // Copyright 2016 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 "core/fpdfapi/fpdf_font/cpdf_cidfont.h"
 
 #include "core/fpdfapi/fpdf_cmaps/cmap_int.h"
 #include "core/fpdfapi/fpdf_font/font_int.h"
@@ skipping 383 matching lines @@
   } else {
     return FALSE;
   }
   if (!m_pCMap) {
     return FALSE;
   }
   m_Charset = m_pCMap->m_Charset;
   if (m_Charset == CIDSET_UNKNOWN) {
     CPDF_Dictionary* pCIDInfo = pCIDFontDict->GetDictBy("CIDSystemInfo");
     if (pCIDInfo) {
-      m_Charset = CharsetFromOrdering(pCIDInfo->GetStringBy("Ordering"));
+      m_Charset =
+          CharsetFromOrdering(pCIDInfo->GetStringBy("Ordering").AsStringC());
     }
   }
   if (m_Charset != CIDSET_UNKNOWN)
     m_pCID2UnicodeMap =
         CPDF_ModuleMgr::Get()
             ->GetPageModule()
             ->GetFontGlobals()
             ->m_CMapManager.GetCID2UnicodeMap(
                 m_Charset,
                 !m_pFontFile && (m_pCMap->m_Coding == CIDCODING_CID ||
@@ skipping 481 matching lines @@
 
 const uint8_t* CPDF_CIDFont::GetCIDTransform(uint16_t CID) const {
   if (m_Charset != CIDSET_JAPAN1 || m_pFontFile)
     return nullptr;
 
   const struct CIDTransform* found = (const struct CIDTransform*)FXSYS_bsearch(
       &CID, g_Japan1_VertCIDs, FX_ArraySize(g_Japan1_VertCIDs),
       sizeof(g_Japan1_VertCIDs[0]), CompareCIDTransform);
   return found ? &found->a : nullptr;
 }