Avoid string allocs for CMap_GetString() return value.

core/fpdfapi/fpdf_font/fpdf_font_cid.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 "core/fpdfapi/fpdf_font/font_int.h"
 
 #include "core/fpdfapi/fpdf_cmaps/cmap_int.h"
 #include "core/fpdfapi/fpdf_font/ttgsubtable.h"
@@ skipping 172 matching lines @@
 };
 
 CIDSet CIDSetFromSizeT(size_t index) {
   if (index >= CIDSET_NUM_SETS) {
     NOTREACHED();
     return CIDSET_UNKNOWN;
   }
   return static_cast<CIDSet>(index);
 }
 
-CFX_ByteString CMap_GetString(const CFX_ByteStringC& word) {
+CFX_ByteStringC CMap_GetString(const CFX_ByteStringC& word) {
   return word.Mid(1, word.GetLength() - 2);
 }
 
 int CompareDWORD(const void* data1, const void* data2) {
   return (*(uint32_t*)data1) - (*(uint32_t*)data2);
 }
 
 int CompareCID(const void* key, const void* element) {
   if ((*(uint32_t*)key) < (*(uint32_t*)element)) {
     return -1;
@@ skipping 196 matching lines @@
         m_pCMap->m_pMapping[code] = (uint16_t)(StartCID + code - StartCode);
       }
     } else {
       uint32_t buf[2];
       buf[0] = StartCode;
       buf[1] = ((EndCode - StartCode) << 16) + StartCID;
       m_AddMaps.AppendBlock(buf, sizeof buf);
     }
     m_CodeSeq = 0;
   } else if (m_Status == 3) {
-    CMap_GetString(word);
     m_Status = 0;
   } else if (m_Status == 4) {
     m_pCMap->m_Charset = CharsetFromOrdering(CMap_GetString(word));
     m_Status = 0;
   } else if (m_Status == 5) {
-    CMap_GetCode(word);
     m_Status = 0;
   } else if (m_Status == 6) {
     m_pCMap->m_bVertical = CMap_GetCode(word);
     m_Status = 0;
   } else if (m_Status == 7) {
     if (word == "endcodespacerange") {
       int nSegs = m_CodeRanges.GetSize();
       if (nSegs > 1) {
         m_pCMap->m_CodingScheme = CPDF_CMap::MixedFourBytes;
         m_pCMap->m_nCodeRanges = nSegs;
@@ skipping 354 matching lines @@
   return 0;
 }
 
 void CPDF_CID2UnicodeMap::Load(CPDF_CMapManager* pMgr,
                                CIDSet charset,
                                FX_BOOL bPromptCJK) {
   m_Charset = charset;
   FPDFAPI_LoadCID2UnicodeMap(charset, m_pEmbeddedMap, m_EmbeddedCount);
 }
 
-CIDSet CharsetFromOrdering(const CFX_ByteString& ordering) {
+CIDSet CharsetFromOrdering(const CFX_ByteStringC& ordering) {
   for (size_t charset = 1; charset < FX_ArraySize(g_CharsetNames); ++charset) {
-    if (ordering == CFX_ByteStringC(g_CharsetNames[charset]))
+    if (ordering == g_CharsetNames[charset])
       return CIDSetFromSizeT(charset);
   }
   return CIDSET_UNKNOWN;
 }