Make down-conversion explicit from CFX_ByteString to CFX_ByteStringC.

Having this happen implicitly can be dangerous because the lifetime
has to be considered; we should have caught the "red bots" in
https://codereview.chromium.org/1847333004/#ps60001 at compile time.

Review URL: https://codereview.chromium.org/1853233002

38 files changed, 187 insertions, 151 deletions

diff --git a/core/fpdfapi/fpdf_edit/cpdf_pagecontentgenerator.cpp b/core/fpdfapi/fpdf_edit/cpdf_pagecontentgenerator.cpp
index 6c5339128b..af79fd31c1 100644
--- a/core/fpdfapi/fpdf_edit/cpdf_pagecontentgenerator.cpp
+++ b/core/fpdfapi/fpdf_edit/cpdf_pagecontentgenerator.cpp
@@ -74,12 +74,13 @@ CFX_ByteString CPDF_PageContentGenerator::RealizeResource(
   int idnum = 1;
   while (1) {
     name.Format("FX%c%d", szType[0], idnum);
-    if (!pResList->KeyExist(name)) {
+    if (!pResList->KeyExist(name.AsByteStringC())) {
       break;
     }
     idnum++;
   }
-  pResList->AddReference(name, m_pDocument, pResourceObj->GetObjNum());
+  pResList->AddReference(name.AsByteStringC(), m_pDocument,
+                         pResourceObj->GetObjNum());
   return name;
 }
 void CPDF_PageContentGenerator::ProcessImage(CFX_ByteTextBuf& buf,
diff --git a/core/fpdfapi/fpdf_edit/fpdf_edit_create.cpp b/core/fpdfapi/fpdf_edit/fpdf_edit_create.cpp
index 21934d35c4..323602b0e1 100644
--- a/core/fpdfapi/fpdf_edit/fpdf_edit_create.cpp
+++ b/core/fpdfapi/fpdf_edit/fpdf_edit_create.cpp
@@ -54,7 +54,7 @@ int32_t PDF_CreatorAppendObject(const CPDF_Object* pObj,
       if (pFile->AppendString(" ") < 0) {
         return -1;
       }
-      if ((len = pFile->AppendString(pObj->GetString())) < 0) {
+      if ((len = pFile->AppendString(pObj->GetString().AsByteStringC())) < 0) {
         return -1;
       }
       offset += len + 1;
@@ -62,7 +62,8 @@ int32_t PDF_CreatorAppendObject(const CPDF_Object* pObj,
     case CPDF_Object::STRING: {
       CFX_ByteString str = pObj->GetString();
       FX_BOOL bHex = pObj->AsString()->IsHex();
-      if ((len = pFile->AppendString(PDF_EncodeString(str, bHex))) < 0) {
+      if ((len = pFile->AppendString(
+               PDF_EncodeString(str, bHex).AsByteStringC())) < 0) {
         return -1;
       }
       offset += len;
@@ -73,7 +74,8 @@ int32_t PDF_CreatorAppendObject(const CPDF_Object* pObj,
         return -1;
       }
       CFX_ByteString str = pObj->GetString();
-      if ((len = pFile->AppendString(PDF_NameEncode(str))) < 0) {
+      if ((len = pFile->AppendString(PDF_NameEncode(str).AsByteStringC())) <
+          0) {
         return -1;
       }
       offset += len + 1;
@@ -132,7 +134,8 @@ int32_t PDF_CreatorAppendObject(const CPDF_Object* pObj,
         if (pFile->AppendString("/") < 0) {
           return -1;
         }
-        if ((len = pFile->AppendString(PDF_NameEncode(key))) < 0) {
+        if ((len = pFile->AppendString(PDF_NameEncode(key).AsByteStringC())) <
+            0) {
           return -1;
         }
         offset += len + 1;
@@ -211,7 +214,8 @@ int32_t PDF_CreatorWriteTrailer(CPDF_Document* pDocument,
       if (pFile->AppendString(("/")) < 0) {
         return -1;
       }
-      if ((len = pFile->AppendString(PDF_NameEncode(key))) < 0) {
+      if ((len = pFile->AppendString(PDF_NameEncode(key).AsByteStringC())) <
+          0) {
         return -1;
       }
       offset += len + 1;
@@ -1114,7 +1118,7 @@ int32_t CPDF_Creator::WriteDirectObj(uint32_t objnum,
       if (m_File.AppendString(" ") < 0) {
         return -1;
       }
-      if ((len = m_File.AppendString(pObj->GetString())) < 0) {
+      if ((len = m_File.AppendString(pObj->GetString().AsByteStringC())) < 0) {
         return -1;
       }
       m_Offset += len + 1;
@@ -1124,7 +1128,7 @@ int32_t CPDF_Creator::WriteDirectObj(uint32_t objnum,
       FX_BOOL bHex = pObj->AsString()->IsHex();
       if (!m_pCryptoHandler || !bEncrypt) {
         CFX_ByteString content = PDF_EncodeString(str, bHex);
-        if ((len = m_File.AppendString(content)) < 0) {
+        if ((len = m_File.AppendString(content.AsByteStringC())) < 0) {
           return -1;
         }
         m_Offset += len;
@@ -1136,7 +1140,7 @@ int32_t CPDF_Creator::WriteDirectObj(uint32_t objnum,
       CFX_ByteString content = PDF_EncodeString(
           CFX_ByteString((const FX_CHAR*)encryptor.m_pData, encryptor.m_dwSize),
           bHex);
-      if ((len = m_File.AppendString(content)) < 0) {
+      if ((len = m_File.AppendString(content.AsByteStringC())) < 0) {
         return -1;
       }
       m_Offset += len;
@@ -1176,7 +1180,8 @@ int32_t CPDF_Creator::WriteDirectObj(uint32_t objnum,
         return -1;
       }
       CFX_ByteString str = pObj->GetString();
-      if ((len = m_File.AppendString(PDF_NameEncode(str))) < 0) {
+      if ((len = m_File.AppendString(PDF_NameEncode(str).AsByteStringC())) <
+          0) {
         return -1;
       }
       m_Offset += len + 1;
@@ -1240,7 +1245,8 @@ int32_t CPDF_Creator::WriteDirectObj(uint32_t objnum,
         if (m_File.AppendString("/") < 0) {
           return -1;
         }
-        if ((len = m_File.AppendString(PDF_NameEncode(key))) < 0) {
+        if ((len = m_File.AppendString(PDF_NameEncode(key).AsByteStringC())) <
+            0) {
           return -1;
         }
         m_Offset += len + 1;
@@ -1642,7 +1648,7 @@ int32_t CPDF_Creator::WriteDoc_Stage3(IFX_Pause* pPause) {
         str = m_ObjectOffset.GetPtrAt(1)
                   ? "xref\r\n"
                   : "xref\r\n0 1\r\n0000000000 65535 f\r\n";
-        if (m_File.AppendString(str) < 0) {
+        if (m_File.AppendString(str.AsByteStringC()) < 0) {
           return -1;
         }
         m_Pos = (void*)(uintptr_t)1;
@@ -1771,7 +1777,7 @@ int32_t CPDF_Creator::WriteDoc_Stage4(IFX_Pause* pPause) {
         if (m_File.AppendString(("/")) < 0) {
           return -1;
         }
-        if (m_File.AppendString(PDF_NameEncode(key)) < 0) {
+        if (m_File.AppendString(PDF_NameEncode(key).AsByteStringC()) < 0) {
           return -1;
         }
         if (pValue->GetObjNum()) {
diff --git a/core/fpdfapi/fpdf_edit/fpdf_edit_doc.cpp b/core/fpdfapi/fpdf_edit/fpdf_edit_doc.cpp
index 0f75cb04a8..d70c04c690 100644
--- a/core/fpdfapi/fpdf_edit/fpdf_edit_doc.cpp
+++ b/core/fpdfapi/fpdf_edit/fpdf_edit_doc.cpp
@@ -1124,7 +1124,7 @@ CPDF_Font* CPDF_Document::AddStandardFont(const FX_CHAR* font,
   CFX_ByteString name(font);
   if (PDF_GetStandardFontName(&name) < 0)
     return nullptr;
-  return GetPageData()->GetStandardFont(name, pEncoding);
+  return GetPageData()->GetStandardFont(name.AsByteStringC(), pEncoding);
 }
 
 void CPDF_Document::DeletePage(int iPage) {
diff --git a/core/fpdfapi/fpdf_font/fpdf_font.cpp b/core/fpdfapi/fpdf_font/fpdf_font.cpp
index ce2390ec08..aff2b72960 100644
--- a/core/fpdfapi/fpdf_font/fpdf_font.cpp
+++ b/core/fpdfapi/fpdf_font/fpdf_font.cpp
@@ -233,9 +233,9 @@ void CPDF_ToUnicodeMap::Load(CPDF_Stream* pStream) {
           break;
         }
         high = parser.GetWord();
-        uint32_t lowcode = StringToCode(low);
-        uint32_t highcode =
-            (lowcode & 0xffffff00) | (StringToCode(high) & 0xff);
+        uint32_t lowcode = StringToCode(low.AsByteStringC());
+        uint32_t highcode = (lowcode & 0xffffff00) |
+                            (StringToCode(high.AsByteStringC()) & 0xff);
         if (highcode == (uint32_t)-1) {
           break;
         }
@@ -243,7 +243,7 @@ void CPDF_ToUnicodeMap::Load(CPDF_Stream* pStream) {
         if (start == "[") {
           for (uint32_t code = lowcode; code <= highcode; code++) {
             CFX_ByteString dest = parser.GetWord();
-            CFX_WideString destcode = StringToWideString(dest);
+            CFX_WideString destcode = StringToWideString(dest.AsByteStringC());
             int len = destcode.GetLength();
             if (len == 0) {
               continue;
@@ -258,11 +258,11 @@ void CPDF_ToUnicodeMap::Load(CPDF_Stream* pStream) {
           }
           parser.GetWord();
         } else {
-          CFX_WideString destcode = StringToWideString(start);
+          CFX_WideString destcode = StringToWideString(start.AsByteStringC());
           int len = destcode.GetLength();
           uint32_t value = 0;
           if (len == 1) {
-            value = StringToCode(start);
+            value = StringToCode(start.AsByteStringC());
             for (uint32_t code = lowcode; code <= highcode; code++) {
               m_Map[code] = value++;
             }
diff --git a/core/fpdfapi/fpdf_font/fpdf_font_cid.cpp b/core/fpdfapi/fpdf_font/fpdf_font_cid.cpp
index 2552a3c0a6..fb3707f498 100644
--- a/core/fpdfapi/fpdf_font/fpdf_font_cid.cpp
+++ b/core/fpdfapi/fpdf_font/fpdf_font_cid.cpp
@@ -440,7 +440,7 @@ void CPDF_CMapParser::ParseWord(const CFX_ByteStringC& word) {
       }
       if (m_CodeSeq % 2) {
         CMap_CodeRange range;
-        if (CMap_GetCodeRange(range, m_LastWord, word)) {
+        if (CMap_GetCodeRange(range, m_LastWord.AsByteStringC(), word)) {
           m_CodeRanges.Add(range);
         }
       }
diff --git a/core/fpdfapi/fpdf_page/cpdf_allstates.cpp b/core/fpdfapi/fpdf_page/cpdf_allstates.cpp
index 159de584ee..d81a488d20 100644
--- a/core/fpdfapi/fpdf_page/cpdf_allstates.cpp
+++ b/core/fpdfapi/fpdf_page/cpdf_allstates.cpp
@@ -115,7 +115,7 @@ void CPDF_AllStates::ProcessExtGS(CPDF_Dictionary* pGS,
         CFX_ByteString mode =
             pArray ? pArray->GetStringAt(0) : pObject->GetString();
 
-        pGeneralState->SetBlendMode(mode);
+        pGeneralState->SetBlendMode(mode.AsByteStringC());
         if (pGeneralState->m_BlendType > FXDIB_BLEND_MULTIPLY) {
           pParser->GetPageObjectHolder()->SetBackgroundAlphaNeeded(TRUE);
         }
diff --git a/core/fpdfapi/fpdf_page/fpdf_page_doc.cpp b/core/fpdfapi/fpdf_page/fpdf_page_doc.cpp
index 9f4ad5a7d5..758ce940d2 100644
--- a/core/fpdfapi/fpdf_page/fpdf_page_doc.cpp
+++ b/core/fpdfapi/fpdf_page/fpdf_page_doc.cpp
@@ -331,7 +331,7 @@ CPDF_ColorSpace* CPDF_DocPageData::GetColorSpace(
     if (!pCS && pResources) {
       CPDF_Dictionary* pList = pResources->GetDictBy("ColorSpace");
       if (pList) {
-        pCSObj = pList->GetDirectObjectBy(name);
+        pCSObj = pList->GetDirectObjectBy(name.AsByteStringC());
         return GetColorSpace(pCSObj, nullptr);
       }
     }
diff --git a/core/fpdfapi/fpdf_page/fpdf_page_parser.cpp b/core/fpdfapi/fpdf_page/fpdf_page_parser.cpp
index daddb9f05b..4f304a3b3b 100644
--- a/core/fpdfapi/fpdf_page/fpdf_page_parser.cpp
+++ b/core/fpdfapi/fpdf_page/fpdf_page_parser.cpp
@@ -566,9 +566,9 @@ void CPDF_StreamContentParser::Handle_BeginImage() {
     if (!key.IsEmpty()) {
       uint32_t dwObjNum = pObj ? pObj->GetObjNum() : 0;
       if (dwObjNum)
-        pDict->SetAtReference(key, m_pDocument, dwObjNum);
+        pDict->SetAtReference(key.AsByteStringC(), m_pDocument, dwObjNum);
       else
-        pDict->SetAt(key, pObj.release());
+        pDict->SetAt(key.AsByteStringC(), pObj.release());
     }
   }
   PDF_ReplaceAbbr(pDict);
@@ -721,7 +721,8 @@ void CPDF_StreamContentParser::Handle_ExecuteXObject() {
       pList = m_pPageResources->GetDictBy("XObject");
     if (!pList)
       return;
-    CPDF_Reference* pRes = ToReference(pList->GetObjectBy(name));
+    CPDF_Reference* pRes =
+        ToReference(pList->GetObjectBy(name.AsByteStringC()));
     if (!pRes)
       return;
 
@@ -1257,7 +1258,7 @@ CPDF_Object* CPDF_StreamContentParser::FindResourceObj(
     if (!pList) {
       return NULL;
     }
-    CPDF_Object* pRes = pList->GetDirectObjectBy(name);
+    CPDF_Object* pRes = pList->GetDirectObjectBy(name.AsByteStringC());
     return pRes;
   }
   CPDF_Dictionary* pList = m_pResources->GetDictBy(type);
@@ -1269,10 +1270,10 @@ CPDF_Object* CPDF_StreamContentParser::FindResourceObj(
     if (!pList) {
       return NULL;
     }
-    CPDF_Object* pRes = pList->GetDirectObjectBy(name);
+    CPDF_Object* pRes = pList->GetDirectObjectBy(name.AsByteStringC());
     return pRes;
   }
-  CPDF_Object* pRes = pList->GetDirectObjectBy(name);
+  CPDF_Object* pRes = pList->GetDirectObjectBy(name.AsByteStringC());
   return pRes;
 }
 
@@ -1763,8 +1764,9 @@ void PDF_ReplaceAbbr(CPDF_Object* pObj) {
       for (const auto& it : *pDict) {
         CFX_ByteString key = it.first;
         CPDF_Object* value = it.second;
-        CFX_ByteStringC fullname = PDF_FindFullName(
-            PDF_InlineKeyAbbr, FX_ArraySize(PDF_InlineKeyAbbr), key);
+        CFX_ByteStringC fullname =
+            PDF_FindFullName(PDF_InlineKeyAbbr, FX_ArraySize(PDF_InlineKeyAbbr),
+                             key.AsByteStringC());
         if (!fullname.IsEmpty()) {
           AbbrReplacementOp op;
           op.is_replace_key = true;
@@ -1777,7 +1779,8 @@ void PDF_ReplaceAbbr(CPDF_Object* pObj) {
         if (value->IsName()) {
           CFX_ByteString name = value->GetString();
           fullname = PDF_FindFullName(PDF_InlineValueAbbr,
-                                      FX_ArraySize(PDF_InlineValueAbbr), name);
+                                      FX_ArraySize(PDF_InlineValueAbbr),
+                                      name.AsByteStringC());
           if (!fullname.IsEmpty()) {
             AbbrReplacementOp op;
             op.is_replace_key = false;
@@ -1791,9 +1794,9 @@ void PDF_ReplaceAbbr(CPDF_Object* pObj) {
       }
       for (const auto& op : replacements) {
         if (op.is_replace_key)
-          pDict->ReplaceKey(op.key, op.replacement);
+          pDict->ReplaceKey(op.key.AsByteStringC(), op.replacement);
         else
-          pDict->SetAtName(op.key, op.replacement);
+          pDict->SetAtName(op.key.AsByteStringC(), op.replacement);
       }
       break;
     }
@@ -1804,7 +1807,8 @@ void PDF_ReplaceAbbr(CPDF_Object* pObj) {
         if (pElement->IsName()) {
           CFX_ByteString name = pElement->GetString();
           CFX_ByteStringC fullname = PDF_FindFullName(
-              PDF_InlineValueAbbr, FX_ArraySize(PDF_InlineValueAbbr), name);
+              PDF_InlineValueAbbr, FX_ArraySize(PDF_InlineValueAbbr),
+              name.AsByteStringC());
           if (!fullname.IsEmpty()) {
             pArray->SetAt(i, new CPDF_Name(fullname));
           }
diff --git a/core/fpdfapi/fpdf_page/fpdf_page_parser_old.cpp b/core/fpdfapi/fpdf_page/fpdf_page_parser_old.cpp
index a5db2d6d20..a3c88c00df 100644
--- a/core/fpdfapi/fpdf_page/fpdf_page_parser_old.cpp
+++ b/core/fpdfapi/fpdf_page/fpdf_page_parser_old.cpp
@@ -427,7 +427,7 @@ CPDF_Object* CPDF_StreamParser::ReadNextObject(FX_BOOL bAllowNestedArray,
         return nullptr;
       }
       if (!key.IsEmpty()) {
-        pDict->SetAt(key, pObj);
+        pDict->SetAt(key.AsByteStringC(), pObj);
       } else {
         pObj->Release();
       }
diff --git a/core/fpdfapi/fpdf_parser/cpdf_name.cpp b/core/fpdfapi/fpdf_parser/cpdf_name.cpp
index db37754b66..a7adf1b3d6 100644
--- a/core/fpdfapi/fpdf_parser/cpdf_name.cpp
+++ b/core/fpdfapi/fpdf_parser/cpdf_name.cpp
@@ -29,7 +29,7 @@ CFX_ByteString CPDF_Name::GetString() const {
 }
 
 CFX_ByteStringC CPDF_Name::GetConstString() const {
-  return CFX_ByteStringC(m_Name);
+  return m_Name.AsByteStringC();
 }
 
 void CPDF_Name::SetString(const CFX_ByteString& str) {
diff --git a/core/fpdfapi/fpdf_parser/cpdf_number.cpp b/core/fpdfapi/fpdf_parser/cpdf_number.cpp
index d2f0503bc1..dbc17d5dd6 100644
--- a/core/fpdfapi/fpdf_parser/cpdf_number.cpp
+++ b/core/fpdfapi/fpdf_parser/cpdf_number.cpp
@@ -47,7 +47,7 @@ const CPDF_Number* CPDF_Number::AsNumber() const {
 }
 
 void CPDF_Number::SetString(const CFX_ByteString& str) {
-  FX_atonum(str, m_bInteger, &m_Integer);
+  FX_atonum(str.AsByteStringC(), m_bInteger, &m_Integer);
 }
 
 CFX_ByteString CPDF_Number::GetString() const {
diff --git a/core/fpdfapi/fpdf_parser/cpdf_object_unittest.cpp b/core/fpdfapi/fpdf_parser/cpdf_object_unittest.cpp
index 2069a161ea..6c1738d5a6 100644
--- a/core/fpdfapi/fpdf_parser/cpdf_object_unittest.cpp
+++ b/core/fpdfapi/fpdf_parser/cpdf_object_unittest.cpp
@@ -135,7 +135,7 @@ class PDFObjectsTest : public testing::Test {
           return false;
         for (CPDF_Dictionary::const_iterator it = dict1->begin();
              it != dict1->end(); ++it) {
-          if (!Equal(it->second, dict2->GetObjectBy(it->first)))
+          if (!Equal(it->second, dict2->GetObjectBy(it->first.AsByteStringC())))
             return false;
         }
         return true;
diff --git a/core/fpdfapi/fpdf_parser/cpdf_parser.cpp b/core/fpdfapi/fpdf_parser/cpdf_parser.cpp
index 305401525c..73ca71ef1a 100644
--- a/core/fpdfapi/fpdf_parser/cpdf_parser.cpp
+++ b/core/fpdfapi/fpdf_parser/cpdf_parser.cpp
@@ -822,10 +822,11 @@ FX_BOOL CPDF_Parser::RebuildCrossRef() {
                           uint32_t dwObjNum =
                               pElement ? pElement->GetObjNum() : 0;
                           if (dwObjNum) {
-                            m_pTrailer->SetAtReference(key, m_pDocument,
-                                                       dwObjNum);
+                            m_pTrailer->SetAtReference(key.AsByteStringC(),
+                                                       m_pDocument, dwObjNum);
                           } else {
-                            m_pTrailer->SetAt(key, pElement->Clone());
+                            m_pTrailer->SetAt(key.AsByteStringC(),
+                                              pElement->Clone());
                           }
                         }
                       }
diff --git a/core/fpdfapi/fpdf_parser/cpdf_standard_security_handler.cpp b/core/fpdfapi/fpdf_parser/cpdf_standard_security_handler.cpp
index ac7667c3ea..9846c40d8f 100644
--- a/core/fpdfapi/fpdf_parser/cpdf_standard_security_handler.cpp
+++ b/core/fpdfapi/fpdf_parser/cpdf_standard_security_handler.cpp
@@ -166,14 +166,15 @@ FX_BOOL CPDF_StandardSecurityHandler::LoadDict(CPDF_Dictionary* pEncryptDict) {
   m_Revision = pEncryptDict->GetIntegerBy("R");
   m_Permissions = pEncryptDict->GetIntegerBy("P", -1);
   if (m_Version < 4) {
-    return _LoadCryptInfo(pEncryptDict, CFX_ByteString(), m_Cipher, m_KeyLen);
+    return _LoadCryptInfo(pEncryptDict, CFX_ByteStringC(), m_Cipher, m_KeyLen);
   }
   CFX_ByteString stmf_name = pEncryptDict->GetStringBy("StmF");
   CFX_ByteString strf_name = pEncryptDict->GetStringBy("StrF");
   if (stmf_name != strf_name) {
     return FALSE;
   }
-  if (!_LoadCryptInfo(pEncryptDict, strf_name, m_Cipher, m_KeyLen)) {
+  if (!_LoadCryptInfo(pEncryptDict, strf_name.AsByteStringC(), m_Cipher,
+                      m_KeyLen)) {
     return FALSE;
   }
   return TRUE;
@@ -195,7 +196,8 @@ FX_BOOL CPDF_StandardSecurityHandler::LoadDict(CPDF_Dictionary* pEncryptDict,
       return FALSE;
     }
   }
-  if (!_LoadCryptInfo(pEncryptDict, strf_name, cipher, key_len)) {
+  if (!_LoadCryptInfo(pEncryptDict, strf_name.AsByteStringC(), cipher,
+                      key_len)) {
     return FALSE;
   }
   m_Cipher = cipher;
diff --git a/core/fpdfapi/fpdf_parser/cpdf_string.cpp b/core/fpdfapi/fpdf_parser/cpdf_string.cpp
index 9a88e937ab..3f04d125a2 100644
--- a/core/fpdfapi/fpdf_parser/cpdf_string.cpp
+++ b/core/fpdfapi/fpdf_parser/cpdf_string.cpp
@@ -32,7 +32,7 @@ CFX_ByteString CPDF_String::GetString() const {
 }
 
 CFX_ByteStringC CPDF_String::GetConstString() const {
-  return CFX_ByteStringC(m_String);
+  return m_String.AsByteStringC();
 }
 
 void CPDF_String::SetString(const CFX_ByteString& str) {
diff --git a/core/fpdfapi/fpdf_parser/cpdf_syntax_parser.cpp b/core/fpdfapi/fpdf_parser/cpdf_syntax_parser.cpp
index 5a3db292e0..d04a682b77 100644
--- a/core/fpdfapi/fpdf_parser/cpdf_syntax_parser.cpp
+++ b/core/fpdfapi/fpdf_parser/cpdf_syntax_parser.cpp
@@ -399,7 +399,7 @@ CPDF_Object* CPDF_SyntaxParser::GetObject(CPDF_IndirectObjectHolder* pObjList,
       }
     }
     m_Pos = SavedPos;
-    return new CPDF_Number(word);
+    return new CPDF_Number(word.AsByteStringC());
   }
 
   if (word == "true" || word == "false")
@@ -521,7 +521,7 @@ CPDF_Object* CPDF_SyntaxParser::GetObjectByStrict(
         return new CPDF_Reference(pObjList, FXSYS_atoui(word));
     }
     m_Pos = SavedPos;
-    return new CPDF_Number(word);
+    return new CPDF_Number(word.AsByteStringC());
   }
 
   if (word == "true" || word == "false")
diff --git a/core/fpdfapi/fpdf_parser/include/cpdf_object.h b/core/fpdfapi/fpdf_parser/include/cpdf_object.h
index 802cbbc638..6cdaaf58fd 100644
--- a/core/fpdfapi/fpdf_parser/include/cpdf_object.h
+++ b/core/fpdfapi/fpdf_parser/include/cpdf_object.h
@@ -46,6 +46,8 @@ class CPDF_Object {
   void Release();
 
   virtual CFX_ByteString GetString() const;
+
+  // Note: |this| must outlive the use of |GetConstString|'s result.
   virtual CFX_ByteStringC GetConstString() const;
   virtual CFX_WideString GetUnicodeText() const;
   virtual FX_FLOAT GetNumber() const;
diff --git a/core/fpdfdoc/cpvt_color.cpp b/core/fpdfdoc/cpvt_color.cpp
index afeff23e15..7ddb9df0d0 100644
--- a/core/fpdfdoc/cpvt_color.cpp
+++ b/core/fpdfdoc/cpvt_color.cpp
@@ -10,7 +10,7 @@
 
 // Static.
 CPVT_Color CPVT_Color::ParseColor(const CFX_ByteString& str) {
-  CPDF_SimpleParser syntax(str);
+  CPDF_SimpleParser syntax(str.AsByteStringC());
   if (syntax.FindTagParamFromStart("g", 1))
     return CPVT_Color(CPVT_Color::kGray, FX_atof(syntax.GetWord()));
 
diff --git a/core/fpdfdoc/cpvt_fontmap.cpp b/core/fpdfdoc/cpvt_fontmap.cpp
index 529f85169e..0aa7ac3486 100644
--- a/core/fpdfdoc/cpvt_fontmap.cpp
+++ b/core/fpdfdoc/cpvt_fontmap.cpp
@@ -38,8 +38,9 @@ void CPVT_FontMap::GetAnnotSysPDFFont(CPDF_Document* pDoc,
     return;
 
   if (CPDF_Dictionary* pFontList = pResDict->GetDictBy("Font")) {
-    if (!pFontList->KeyExist(sSysFontAlias))
-      pFontList->SetAtReference(sSysFontAlias, pDoc, pPDFFont->GetFontDict());
+    if (!pFontList->KeyExist(sSysFontAlias.AsByteStringC()))
+      pFontList->SetAtReference(sSysFontAlias.AsByteStringC(), pDoc,
+                                pPDFFont->GetFontDict());
   }
   pSysFont = pPDFFont;
 }
diff --git a/core/fpdfdoc/cpvt_generateap.cpp b/core/fpdfdoc/cpvt_generateap.cpp
index dd935de61e..c5e2cc7fab 100644
--- a/core/fpdfdoc/cpvt_generateap.cpp
+++ b/core/fpdfdoc/cpvt_generateap.cpp
@@ -36,7 +36,7 @@ FX_BOOL GenerateWidgetAP(CPDF_Document* pDoc,
   if (DA.IsEmpty())
     return FALSE;
 
-  CPDF_SimpleParser syntax(DA);
+  CPDF_SimpleParser syntax(DA.AsByteStringC());
   syntax.FindTagParamFromStart("Tf", 2);
   CFX_ByteString sFontName = syntax.GetWord();
   sFontName = PDF_NameDecode(sFontName);
@@ -54,12 +54,12 @@ FX_BOOL GenerateWidgetAP(CPDF_Document* pDoc,
   }
   CPDF_Dictionary* pDRFontDict = pDRDict ? pDRDict->GetDictBy("Font") : nullptr;
   if (pDRFontDict) {
-    pFontDict = pDRFontDict->GetDictBy(sFontName.Mid(1));
+    pFontDict = pDRFontDict->GetDictBy(sFontName.Mid(1).AsByteStringC());
     if (!pFontDict && !bUseFormRes) {
       pDRDict = pFormDict->GetDictBy("DR");
       pDRFontDict = pDRDict->GetDictBy("Font");
       if (pDRFontDict)
-        pFontDict = pDRFontDict->GetDictBy(sFontName.Mid(1));
+        pFontDict = pDRFontDict->GetDictBy(sFontName.Mid(1).AsByteStringC());
     }
   }
   if (!pDRFontDict)
@@ -72,7 +72,8 @@ FX_BOOL GenerateWidgetAP(CPDF_Document* pDoc,
     pFontDict->SetAtName("BaseFont", "Helvetica");
     pFontDict->SetAtName("Encoding", "WinAnsiEncoding");
     pDoc->AddIndirectObject(pFontDict);
-    pDRFontDict->SetAtReference(sFontName.Mid(1), pDoc, pFontDict);
+    pDRFontDict->SetAtReference(sFontName.Mid(1).AsByteStringC(), pDoc,
+                                pFontDict);
   }
   CPDF_Font* pDefFont = pDoc->LoadFont(pFontDict);
   if (!pDefFont)
@@ -189,8 +190,9 @@ FX_BOOL GenerateWidgetAP(CPDF_Document* pDoc,
         pStreamResFontList = new CPDF_Dictionary;
         pStreamResList->SetAt("Font", pStreamResFontList);
       }
-      if (!pStreamResFontList->KeyExist(sFontName))
-        pStreamResFontList->SetAtReference(sFontName, pDoc, pFontDict);
+      if (!pStreamResFontList->KeyExist(sFontName.AsByteStringC()))
+        pStreamResFontList->SetAtReference(sFontName.AsByteStringC(), pDoc,
+                                           pFontDict);
     } else {
       pStreamDict->SetAt("Resources", pFormDict->GetDictBy("DR")->Clone());
       pStreamResList = pStreamDict->GetDictBy("Resources");
@@ -435,8 +437,9 @@ FX_BOOL GenerateWidgetAP(CPDF_Document* pDoc,
           pStreamResFontList = new CPDF_Dictionary;
           pStreamResList->SetAt("Font", pStreamResFontList);
         }
-        if (!pStreamResFontList->KeyExist(sFontName))
-          pStreamResFontList->SetAtReference(sFontName, pDoc, pFontDict);
+        if (!pStreamResFontList->KeyExist(sFontName.AsByteStringC()))
+          pStreamResFontList->SetAtReference(sFontName.AsByteStringC(), pDoc,
+                                             pFontDict);
       } else {
         pStreamDict->SetAt("Resources", pFormDict->GetDictBy("DR")->Clone());
         pStreamResList = pStreamDict->GetDictBy("Resources");
diff --git a/core/fpdfdoc/doc_action.cpp b/core/fpdfdoc/doc_action.cpp
index 2f08bfa3af..9a43b58e98 100644
--- a/core/fpdfdoc/doc_action.cpp
+++ b/core/fpdfdoc/doc_action.cpp
@@ -38,8 +38,8 @@ CPDF_Dest CPDF_Action::GetDest(CPDF_Document* pDoc) const {
   }
   if (pDest->IsString() || pDest->IsName()) {
     CPDF_NameTree name_tree(pDoc, "Dests");
-    CFX_ByteStringC name = pDest->GetString();
-    return CPDF_Dest(name_tree.LookupNamedDest(pDoc, name));
+    return CPDF_Dest(
+        name_tree.LookupNamedDest(pDoc, pDest->GetString().AsByteStringC()));
   }
   if (CPDF_Array* pArray = pDest->AsArray())
     return CPDF_Dest(pArray);
diff --git a/core/fpdfdoc/doc_annot.cpp b/core/fpdfdoc/doc_annot.cpp
index 276516589a..ca900acb9a 100644
--- a/core/fpdfdoc/doc_annot.cpp
+++ b/core/fpdfdoc/doc_annot.cpp
@@ -181,12 +181,12 @@ CPDF_Stream* FPDFDOC_GetAnnotAP(CPDF_Dictionary* pAnnotDict,
         CPDF_Dictionary* pDict = pAnnotDict->GetDictBy("Parent");
         value = pDict ? pDict->GetStringBy("V") : CFX_ByteString();
       }
-      if (value.IsEmpty() || !pDict->KeyExist(value))
+      if (value.IsEmpty() || !pDict->KeyExist(value.AsByteStringC()))
         as = "Off";
       else
         as = value;
     }
-    return pDict->GetStreamBy(as);
+    return pDict->GetStreamBy(as.AsByteStringC());
   }
   return nullptr;
 }
diff --git a/core/fpdfdoc/doc_basic.cpp b/core/fpdfdoc/doc_basic.cpp
index c711709e73..0c7f895405 100644
--- a/core/fpdfdoc/doc_basic.cpp
+++ b/core/fpdfdoc/doc_basic.cpp
@@ -90,12 +90,13 @@ static CPDF_Object* SearchNameNode(CPDF_Dictionary* pNode,
   if (pLimits) {
     CFX_ByteString csLeft = pLimits->GetStringAt(0);
     CFX_ByteString csRight = pLimits->GetStringAt(1);
-    if (csLeft.Compare(csRight) > 0) {
+    if (csLeft.Compare(csRight.AsByteStringC()) > 0) {
       CFX_ByteString csTmp = csRight;
       csRight = csLeft;
       csLeft = csTmp;
     }
-    if (csName.Compare(csLeft) < 0 || csName.Compare(csRight) > 0) {
+    if (csName.Compare(csLeft.AsByteStringC()) < 0 ||
+        csName.Compare(csRight.AsByteStringC()) > 0) {
       return NULL;
     }
   }
@@ -104,7 +105,7 @@ static CPDF_Object* SearchNameNode(CPDF_Dictionary* pNode,
     uint32_t dwCount = pNames->GetCount() / 2;
     for (uint32_t i = 0; i < dwCount; i++) {
       CFX_ByteString csValue = pNames->GetStringAt(i * 2);
-      int32_t iCompare = csValue.Compare(csName);
+      int32_t iCompare = csValue.Compare(csName.AsByteStringC());
       if (iCompare <= 0) {
         if (ppFind) {
           *ppFind = pNames;
@@ -500,7 +501,7 @@ int32_t CPDF_PageLabel::GetPageByLabel(const CFX_ByteStringC& bsLabel) const {
   CFX_ByteString bsOrig = bsLabel;
   for (int i = 0; i < nPages; i++) {
     bsLbl = PDF_EncodeText(GetLabel(i));
-    if (!bsLbl.Compare(bsOrig)) {
+    if (!bsLbl.Compare(bsOrig.AsByteStringC())) {
       return i;
     }
   }
@@ -512,6 +513,5 @@ int32_t CPDF_PageLabel::GetPageByLabel(const CFX_ByteStringC& bsLabel) const {
   return -1;
 }
 int32_t CPDF_PageLabel::GetPageByLabel(const CFX_WideStringC& wsLabel) const {
-  CFX_ByteString bsLabel = PDF_EncodeText(wsLabel.GetPtr());
-  return GetPageByLabel(bsLabel);
+  return GetPageByLabel(PDF_EncodeText(wsLabel.GetPtr()).AsByteStringC());
 }
diff --git a/core/fpdfdoc/doc_bookmark.cpp b/core/fpdfdoc/doc_bookmark.cpp
index 22ff7921ef..35a04043fe 100644
--- a/core/fpdfdoc/doc_bookmark.cpp
+++ b/core/fpdfdoc/doc_bookmark.cpp
@@ -80,8 +80,8 @@ CPDF_Dest CPDF_Bookmark::GetDest(CPDF_Document* pDocument) const {
     return CPDF_Dest();
   if (pDest->IsString() || pDest->IsName()) {
     CPDF_NameTree name_tree(pDocument, "Dests");
-    CFX_ByteStringC name = pDest->GetString();
-    return CPDF_Dest(name_tree.LookupNamedDest(pDocument, name));
+    return CPDF_Dest(name_tree.LookupNamedDest(
+        pDocument, pDest->GetString().AsByteStringC()));
   }
   if (CPDF_Array* pArray = pDest->AsArray())
     return CPDF_Dest(pArray);
diff --git a/core/fpdfdoc/doc_form.cpp b/core/fpdfdoc/doc_form.cpp
index 2a6d739549..aa4b5c9f30 100644
--- a/core/fpdfdoc/doc_form.cpp
+++ b/core/fpdfdoc/doc_form.cpp
@@ -343,8 +343,9 @@ CFX_ByteString CPDF_InterForm::GenerateNewResourceName(
   int num = 0;
   CFX_ByteString bsNum;
   while (TRUE) {
-    if (!pDict->KeyExist(csTmp + bsNum)) {
-      return csTmp + bsNum;
+    CFX_ByteString csKey = csTmp + bsNum;
+    if (!pDict->KeyExist(csKey.AsByteStringC())) {
+      return csKey;
     }
     if (m < iCount) {
       csTmp += csStr[m++];
diff --git a/core/fpdfdoc/doc_formcontrol.cpp b/core/fpdfdoc/doc_formcontrol.cpp
index 1fcc4a386b..0a0a8c9a03 100644
--- a/core/fpdfdoc/doc_formcontrol.cpp
+++ b/core/fpdfdoc/doc_formcontrol.cpp
@@ -78,7 +78,7 @@ void CPDF_FormControl::SetOnStateName(const CFX_ByteString& csOn) {
         continue;
       }
       if (csKey2 != "Off") {
-        pSubDict->ReplaceKey(csKey2, csValue);
+        pSubDict->ReplaceKey(csKey2.AsByteStringC(), csValue.AsByteStringC());
         break;
       }
     }
@@ -202,7 +202,7 @@ CPDF_ApSettings CPDF_FormControl::GetMK() const {
 }
 
 bool CPDF_FormControl::HasMKEntry(CFX_ByteString csEntry) const {
-  return GetMK().HasMKEntry(csEntry);
+  return GetMK().HasMKEntry(csEntry.AsByteStringC());
 }
 
 int CPDF_FormControl::GetRotation() {
@@ -210,24 +210,24 @@ int CPDF_FormControl::GetRotation() {
 }
 
 FX_ARGB CPDF_FormControl::GetColor(int& iColorType, CFX_ByteString csEntry) {
-  return GetMK().GetColor(iColorType, csEntry);
+  return GetMK().GetColor(iColorType, csEntry.AsByteStringC());
 }
 
 FX_FLOAT CPDF_FormControl::GetOriginalColor(int index, CFX_ByteString csEntry) {
-  return GetMK().GetOriginalColor(index, csEntry);
+  return GetMK().GetOriginalColor(index, csEntry.AsByteStringC());
 }
 
 void CPDF_FormControl::GetOriginalColor(int& iColorType,
                                         FX_FLOAT fc[4],
                                         CFX_ByteString csEntry) {
-  GetMK().GetOriginalColor(iColorType, fc, csEntry);
+  GetMK().GetOriginalColor(iColorType, fc, csEntry.AsByteStringC());
 }
 CFX_WideString CPDF_FormControl::GetCaption(CFX_ByteString csEntry) {
-  return GetMK().GetCaption(csEntry);
+  return GetMK().GetCaption(csEntry.AsByteStringC());
 }
 
 CPDF_Stream* CPDF_FormControl::GetIcon(CFX_ByteString csEntry) {
-  return GetMK().GetIcon(csEntry);
+  return GetMK().GetIcon(csEntry.AsByteStringC());
 }
 
 CPDF_IconFit CPDF_FormControl::GetIconFit() {
@@ -286,7 +286,8 @@ CPDF_Font* CPDF_FormControl::GetDefaultControlFont() {
   if (CPDF_Dictionary* pDict = ToDictionary(pObj)) {
     CPDF_Dictionary* pFonts = pDict->GetDictBy("Font");
     if (pFonts) {
-      CPDF_Dictionary* pElement = pFonts->GetDictBy(csFontNameTag);
+      CPDF_Dictionary* pElement =
+          pFonts->GetDictBy(csFontNameTag.AsByteStringC());
       if (pElement) {
         CPDF_Font* pFont = m_pField->m_pForm->m_pDocument->LoadFont(pElement);
         if (pFont) {
@@ -303,7 +304,8 @@ CPDF_Font* CPDF_FormControl::GetDefaultControlFont() {
   if (CPDF_Dictionary* pDict = ToDictionary(pObj)) {
     CPDF_Dictionary* pFonts = pDict->GetDictBy("Font");
     if (pFonts) {
-      CPDF_Dictionary* pElement = pFonts->GetDictBy(csFontNameTag);
+      CPDF_Dictionary* pElement =
+          pFonts->GetDictBy(csFontNameTag.AsByteStringC());
       if (pElement) {
         CPDF_Font* pFont = m_pField->m_pForm->m_pDocument->LoadFont(pElement);
         if (pFont) {
diff --git a/core/fpdfdoc/doc_formfield.cpp b/core/fpdfdoc/doc_formfield.cpp
index 0f8b3dd5ea..931f9e18d9 100644
--- a/core/fpdfdoc/doc_formfield.cpp
+++ b/core/fpdfdoc/doc_formfield.cpp
@@ -1054,7 +1054,7 @@ void CPDF_FormField::LoadDA() {
   if (DA.IsEmpty()) {
     return;
   }
-  CPDF_SimpleParser syntax(DA);
+  CPDF_SimpleParser syntax(DA.AsByteStringC());
   syntax.FindTagParamFromStart("Tf", 2);
   CFX_ByteString font_name = syntax.GetWord();
   CPDF_Dictionary* pFontDict = NULL;
@@ -1062,7 +1062,7 @@ void CPDF_FormField::LoadDA() {
       m_pForm->m_pFormDict->GetDictBy("DR")->GetDictBy("Font"))
     pFontDict = m_pForm->m_pFormDict->GetDictBy("DR")
                     ->GetDictBy("Font")
-                    ->GetDictBy(font_name);
+                    ->GetDictBy(font_name.AsByteStringC());
 
   if (!pFontDict) {
     return;
diff --git a/core/fpdfdoc/doc_link.cpp b/core/fpdfdoc/doc_link.cpp
index 723955f9ea..d86bf203e4 100644
--- a/core/fpdfdoc/doc_link.cpp
+++ b/core/fpdfdoc/doc_link.cpp
@@ -81,8 +81,8 @@ CPDF_Dest CPDF_Link::GetDest(CPDF_Document* pDoc) {
 
   if (pDest->IsString() || pDest->IsName()) {
     CPDF_NameTree name_tree(pDoc, "Dests");
-    CFX_ByteStringC name = pDest->GetString();
-    return CPDF_Dest(name_tree.LookupNamedDest(pDoc, name));
+    return CPDF_Dest(
+        name_tree.LookupNamedDest(pDoc, pDest->GetString().AsByteStringC()));
   }
   if (CPDF_Array* pArray = pDest->AsArray())
     return CPDF_Dest(pArray);
diff --git a/core/fpdfdoc/doc_ocg.cpp b/core/fpdfdoc/doc_ocg.cpp
index a739c1675c..7464936b62 100644
--- a/core/fpdfdoc/doc_ocg.cpp
+++ b/core/fpdfdoc/doc_ocg.cpp
@@ -142,7 +142,7 @@ FX_BOOL CPDF_OCContext::LoadOCGStateFromConfig(const CFX_ByteStringC& csConfig,
       if (!pState) {
         continue;
       }
-      bState = pState->GetStringBy(csFind) != "OFF";
+      bState = pState->GetStringBy(csFind.AsByteStringC()) != "OFF";
     }
   }
   return bState;
@@ -154,11 +154,11 @@ FX_BOOL CPDF_OCContext::LoadOCGState(const CPDF_Dictionary* pOCGDict) const {
   CFX_ByteString csState = FPDFDOC_OCG_GetUsageTypeString(m_eUsageType);
   CPDF_Dictionary* pUsage = pOCGDict->GetDictBy("Usage");
   if (pUsage) {
-    CPDF_Dictionary* pState = pUsage->GetDictBy(csState);
+    CPDF_Dictionary* pState = pUsage->GetDictBy(csState.AsByteStringC());
     if (pState) {
       CFX_ByteString csFind = csState + "State";
-      if (pState->KeyExist(csFind)) {
-        return pState->GetStringBy(csFind) != "OFF";
+      if (pState->KeyExist(csFind.AsByteStringC())) {
+        return pState->GetStringBy(csFind.AsByteStringC()) != "OFF";
       }
     }
     if (csState != "View") {
@@ -169,7 +169,7 @@ FX_BOOL CPDF_OCContext::LoadOCGState(const CPDF_Dictionary* pOCGDict) const {
     }
   }
   FX_BOOL bDefValid = FALSE;
-  return LoadOCGStateFromConfig(csState, pOCGDict, bDefValid);
+  return LoadOCGStateFromConfig(csState.AsByteStringC(), pOCGDict, bDefValid);
 }
 
 FX_BOOL CPDF_OCContext::GetOCGVisible(const CPDF_Dictionary* pOCGDict) {
diff --git a/core/fpdfdoc/doc_tagged.cpp b/core/fpdfdoc/doc_tagged.cpp
index 684789acc2..2a3554c499 100644
--- a/core/fpdfdoc/doc_tagged.cpp
+++ b/core/fpdfdoc/doc_tagged.cpp
@@ -205,7 +205,8 @@ CPDF_StructElementImpl::CPDF_StructElementImpl(CPDF_StructTreeImpl* pTree,
   m_pDict = pDict;
   m_Type = pDict->GetStringBy("S");
   if (pTree->m_pRoleMap) {
-    CFX_ByteString mapped = pTree->m_pRoleMap->GetStringBy(m_Type);
+    CFX_ByteString mapped =
+        pTree->m_pRoleMap->GetStringBy(m_Type.AsByteStringC());
     if (!mapped.IsEmpty()) {
       m_Type = mapped;
     }
@@ -373,14 +374,16 @@ CPDF_Object* CPDF_StructElementImpl::GetAttr(const CFX_ByteStringC& owner,
   if (CPDF_Array* pArray = pC->AsArray()) {
     for (uint32_t i = 0; i < pArray->GetCount(); i++) {
       CFX_ByteString class_name = pArray->GetStringAt(i);
-      CPDF_Dictionary* pClassDict = pClassMap->GetDictBy(class_name);
+      CPDF_Dictionary* pClassDict =
+          pClassMap->GetDictBy(class_name.AsByteStringC());
       if (pClassDict && pClassDict->GetStringBy("O") == owner)
         return pClassDict->GetDirectObjectBy(name);
     }
     return nullptr;
   }
   CFX_ByteString class_name = pC->GetString();
-  CPDF_Dictionary* pClassDict = pClassMap->GetDictBy(class_name);
+  CPDF_Dictionary* pClassDict =
+      pClassMap->GetDictBy(class_name.AsByteStringC());
   if (pClassDict && pClassDict->GetStringBy("O") == owner)
     return pClassDict->GetDirectObjectBy(name);
   return nullptr;
diff --git a/core/fpdfdoc/doc_utils.cpp b/core/fpdfdoc/doc_utils.cpp
index f83d001af5..d3b3cac627 100644
--- a/core/fpdfdoc/doc_utils.cpp
+++ b/core/fpdfdoc/doc_utils.cpp
@@ -82,7 +82,7 @@ FX_BOOL CPDF_DefaultAppearance::HasFont() {
   if (m_csDA.IsEmpty()) {
     return FALSE;
   }
-  CPDF_SimpleParser syntax(m_csDA);
+  CPDF_SimpleParser syntax(m_csDA.AsByteStringC());
   return syntax.FindTagParamFromStart("Tf", 2);
 }
 CFX_ByteString CPDF_DefaultAppearance::GetFontString() {
@@ -90,7 +90,7 @@ CFX_ByteString CPDF_DefaultAppearance::GetFontString() {
   if (m_csDA.IsEmpty()) {
     return csFont;
   }
-  CPDF_SimpleParser syntax(m_csDA);
+  CPDF_SimpleParser syntax(m_csDA.AsByteStringC());
   if (syntax.FindTagParamFromStart("Tf", 2)) {
     csFont += (CFX_ByteString)syntax.GetWord();
     csFont += " ";
@@ -107,11 +107,11 @@ void CPDF_DefaultAppearance::GetFont(CFX_ByteString& csFontNameTag,
   if (m_csDA.IsEmpty()) {
     return;
   }
-  CPDF_SimpleParser syntax(m_csDA);
+  CPDF_SimpleParser syntax(m_csDA.AsByteStringC());
   if (syntax.FindTagParamFromStart("Tf", 2)) {
-    csFontNameTag = (CFX_ByteString)syntax.GetWord();
+    csFontNameTag = CFX_ByteString(syntax.GetWord());
     csFontNameTag.Delete(0, 1);
-    fFontSize = FX_atof((CFX_ByteString)syntax.GetWord());
+    fFontSize = FX_atof(syntax.GetWord());
   }
   csFontNameTag = PDF_NameDecode(csFontNameTag);
 }
@@ -119,7 +119,7 @@ FX_BOOL CPDF_DefaultAppearance::HasColor(FX_BOOL bStrokingOperation) {
   if (m_csDA.IsEmpty()) {
     return FALSE;
   }
-  CPDF_SimpleParser syntax(m_csDA);
+  CPDF_SimpleParser syntax(m_csDA.AsByteStringC());
   if (syntax.FindTagParamFromStart(bStrokingOperation ? "G" : "g", 1)) {
     return TRUE;
   }
@@ -134,7 +134,7 @@ CFX_ByteString CPDF_DefaultAppearance::GetColorString(
   if (m_csDA.IsEmpty()) {
     return csColor;
   }
-  CPDF_SimpleParser syntax(m_csDA);
+  CPDF_SimpleParser syntax(m_csDA.AsByteStringC());
   if (syntax.FindTagParamFromStart(bStrokingOperation ? "G" : "g", 1)) {
     csColor += (CFX_ByteString)syntax.GetWord();
     csColor += " ";
@@ -174,25 +174,25 @@ void CPDF_DefaultAppearance::GetColor(int& iColorType,
   if (m_csDA.IsEmpty()) {
     return;
   }
-  CPDF_SimpleParser syntax(m_csDA);
+  CPDF_SimpleParser syntax(m_csDA.AsByteStringC());
   if (syntax.FindTagParamFromStart(bStrokingOperation ? "G" : "g", 1)) {
     iColorType = COLORTYPE_GRAY;
-    fc[0] = FX_atof((CFX_ByteString)syntax.GetWord());
+    fc[0] = FX_atof(syntax.GetWord());
     return;
   }
   if (syntax.FindTagParamFromStart(bStrokingOperation ? "RG" : "rg", 3)) {
     iColorType = COLORTYPE_RGB;
-    fc[0] = FX_atof((CFX_ByteString)syntax.GetWord());
-    fc[1] = FX_atof((CFX_ByteString)syntax.GetWord());
-    fc[2] = FX_atof((CFX_ByteString)syntax.GetWord());
+    fc[0] = FX_atof(syntax.GetWord());
+    fc[1] = FX_atof(syntax.GetWord());
+    fc[2] = FX_atof(syntax.GetWord());
     return;
   }
   if (syntax.FindTagParamFromStart(bStrokingOperation ? "K" : "k", 4)) {
     iColorType = COLORTYPE_CMYK;
-    fc[0] = FX_atof((CFX_ByteString)syntax.GetWord());
-    fc[1] = FX_atof((CFX_ByteString)syntax.GetWord());
-    fc[2] = FX_atof((CFX_ByteString)syntax.GetWord());
-    fc[3] = FX_atof((CFX_ByteString)syntax.GetWord());
+    fc[0] = FX_atof(syntax.GetWord());
+    fc[1] = FX_atof(syntax.GetWord());
+    fc[2] = FX_atof(syntax.GetWord());
+    fc[3] = FX_atof(syntax.GetWord());
   }
 }
 void CPDF_DefaultAppearance::GetColor(FX_ARGB& color,
@@ -203,27 +203,27 @@ void CPDF_DefaultAppearance::GetColor(FX_ARGB& color,
   if (m_csDA.IsEmpty()) {
     return;
   }
-  CPDF_SimpleParser syntax(m_csDA);
+  CPDF_SimpleParser syntax(m_csDA.AsByteStringC());
   if (syntax.FindTagParamFromStart(bStrokingOperation ? "G" : "g", 1)) {
     iColorType = COLORTYPE_GRAY;
-    FX_FLOAT g = FX_atof((CFX_ByteString)syntax.GetWord()) * 255 + 0.5f;
+    FX_FLOAT g = FX_atof(syntax.GetWord()) * 255 + 0.5f;
     color = ArgbEncode(255, (int)g, (int)g, (int)g);
     return;
   }
   if (syntax.FindTagParamFromStart(bStrokingOperation ? "RG" : "rg", 3)) {
     iColorType = COLORTYPE_RGB;
-    FX_FLOAT r = FX_atof((CFX_ByteString)syntax.GetWord()) * 255 + 0.5f;
-    FX_FLOAT g = FX_atof((CFX_ByteString)syntax.GetWord()) * 255 + 0.5f;
-    FX_FLOAT b = FX_atof((CFX_ByteString)syntax.GetWord()) * 255 + 0.5f;
+    FX_FLOAT r = FX_atof(syntax.GetWord()) * 255 + 0.5f;
+    FX_FLOAT g = FX_atof(syntax.GetWord()) * 255 + 0.5f;
+    FX_FLOAT b = FX_atof(syntax.GetWord()) * 255 + 0.5f;
     color = ArgbEncode(255, (int)r, (int)g, (int)b);
     return;
   }
   if (syntax.FindTagParamFromStart(bStrokingOperation ? "K" : "k", 4)) {
     iColorType = COLORTYPE_CMYK;
-    FX_FLOAT c = FX_atof((CFX_ByteString)syntax.GetWord());
-    FX_FLOAT m = FX_atof((CFX_ByteString)syntax.GetWord());
-    FX_FLOAT y = FX_atof((CFX_ByteString)syntax.GetWord());
-    FX_FLOAT k = FX_atof((CFX_ByteString)syntax.GetWord());
+    FX_FLOAT c = FX_atof(syntax.GetWord());
+    FX_FLOAT m = FX_atof(syntax.GetWord());
+    FX_FLOAT y = FX_atof(syntax.GetWord());
+    FX_FLOAT k = FX_atof(syntax.GetWord());
     FX_FLOAT r = 1.0f - std::min(1.0f, c + k);
     FX_FLOAT g = 1.0f - std::min(1.0f, m + k);
     FX_FLOAT b = 1.0f - std::min(1.0f, y + k);
@@ -235,7 +235,7 @@ FX_BOOL CPDF_DefaultAppearance::HasTextMatrix() {
   if (m_csDA.IsEmpty()) {
     return FALSE;
   }
-  CPDF_SimpleParser syntax(m_csDA);
+  CPDF_SimpleParser syntax(m_csDA.AsByteStringC());
   return syntax.FindTagParamFromStart("Tm", 6);
 }
 CFX_ByteString CPDF_DefaultAppearance::GetTextMatrixString() {
@@ -243,7 +243,7 @@ CFX_ByteString CPDF_DefaultAppearance::GetTextMatrixString() {
   if (m_csDA.IsEmpty()) {
     return csTM;
   }
-  CPDF_SimpleParser syntax(m_csDA);
+  CPDF_SimpleParser syntax(m_csDA.AsByteStringC());
   if (syntax.FindTagParamFromStart("Tm", 6)) {
     for (int i = 0; i < 6; i++) {
       csTM += (CFX_ByteString)syntax.GetWord();
@@ -258,11 +258,11 @@ CFX_Matrix CPDF_DefaultAppearance::GetTextMatrix() {
   if (m_csDA.IsEmpty()) {
     return tm;
   }
-  CPDF_SimpleParser syntax(m_csDA);
+  CPDF_SimpleParser syntax(m_csDA.AsByteStringC());
   if (syntax.FindTagParamFromStart("Tm", 6)) {
     FX_FLOAT f[6];
     for (int i = 0; i < 6; i++) {
-      f[i] = FX_atof((CFX_ByteString)syntax.GetWord());
+      f[i] = FX_atof(syntax.GetWord());
     }
     tm.Set(f[0], f[1], f[2], f[3], f[4], f[5]);
   }
@@ -387,7 +387,7 @@ CPDF_Font* GetInterFormFont(CPDF_Dictionary* pFormDict,
   if (!pFonts) {
     return NULL;
   }
-  CPDF_Dictionary* pElement = pFonts->GetDictBy(csAlias);
+  CPDF_Dictionary* pElement = pFonts->GetDictBy(csAlias.AsByteStringC());
   if (!pElement) {
     return NULL;
   }
@@ -606,7 +606,8 @@ void AddInterFormFont(CPDF_Dictionary*& pFormDict,
   csNameTag.Remove(' ');
   csNameTag =
       CPDF_InterForm::GenerateNewResourceName(pDR, "Font", 4, csNameTag);
-  pFonts->SetAtReference(csNameTag, pDocument, pFont->GetFontDict());
+  pFonts->SetAtReference(csNameTag.AsByteStringC(), pDocument,
+                         pFont->GetFontDict());
 }
 CPDF_Font* AddNativeInterFormFont(CPDF_Dictionary*& pFormDict,
                                   CPDF_Document* pDocument,
@@ -650,7 +651,7 @@ void RemoveInterFormFont(CPDF_Dictionary* pFormDict, const CPDF_Font* pFont) {
   }
   CPDF_Dictionary* pDR = pFormDict->GetDictBy("DR");
   CPDF_Dictionary* pFonts = pDR->GetDictBy("Font");
-  pFonts->RemoveAt(csTag);
+  pFonts->RemoveAt(csTag.AsByteStringC());
 }
 void RemoveInterFormFont(CPDF_Dictionary* pFormDict, CFX_ByteString csNameTag) {
   if (!pFormDict || csNameTag.IsEmpty()) {
@@ -664,7 +665,7 @@ void RemoveInterFormFont(CPDF_Dictionary* pFormDict, CFX_ByteString csNameTag) {
   if (!pFonts) {
     return;
   }
-  pFonts->RemoveAt(csNameTag);
+  pFonts->RemoveAt(csNameTag.AsByteStringC());
 }
 
 CPDF_Font* GetDefaultInterFormFont(CPDF_Dictionary* pFormDict,
diff --git a/core/fxcrt/fx_basic_buffer.cpp b/core/fxcrt/fx_basic_buffer.cpp
index 28c8ac0f32..de7bff2401 100644
--- a/core/fxcrt/fx_basic_buffer.cpp
+++ b/core/fxcrt/fx_basic_buffer.cpp
@@ -248,7 +248,7 @@ CFX_ArchiveSaver& CFX_ArchiveSaver::operator<<(const FX_WCHAR* wstr) {
 }
 CFX_ArchiveSaver& CFX_ArchiveSaver::operator<<(const CFX_WideString& wstr) {
   CFX_ByteString encoded = wstr.UTF16LE_Encode();
-  return operator<<(encoded);
+  return operator<<(encoded.AsByteStringC());
 }
 void CFX_ArchiveSaver::Write(const void* pData, FX_STRSIZE dwSize) {
   if (m_pStream) {
diff --git a/core/fxcrt/fx_xml_parser.cpp b/core/fxcrt/fx_xml_parser.cpp
index 9cdf73ca90..b39c32bfbd 100644
--- a/core/fxcrt/fx_xml_parser.cpp
+++ b/core/fxcrt/fx_xml_parser.cpp
@@ -371,7 +371,7 @@ CXML_Element* CXML_Parser::ParseElement(CXML_Element* pParent,
   }
   CXML_Element* pElement = new CXML_Element;
   pElement->m_pParent = pParent;
-  pElement->SetTag(tag_space, tag_name);
+  pElement->SetTag(tag_space.AsByteStringC(), tag_name.AsByteStringC());
   do {
     CFX_ByteString attr_space, attr_name;
     while (m_dwIndex < m_dwBufferSize) {
@@ -397,7 +397,8 @@ CXML_Element* CXML_Parser::ParseElement(CXML_Element* pParent,
       }
       CFX_WideString attr_value;
       GetAttrValue(attr_value);
-      pElement->m_AttrMap.SetAt(attr_space, attr_name, attr_value);
+      pElement->m_AttrMap.SetAt(attr_space.AsByteStringC(),
+                                attr_name.AsByteStringC(), attr_value);
     }
     m_nOffset = m_nBufferOffset + (FX_FILESIZE)m_dwIndex;
     if (m_dwIndex < m_dwBufferSize || IsEOF()) {
@@ -600,7 +601,7 @@ CFX_ByteString CXML_Element::GetNamespace(FX_BOOL bQualified) const {
   if (bQualified) {
     return m_QSpaceName;
   }
-  return GetNamespaceURI(m_QSpaceName);
+  return GetNamespaceURI(m_QSpaceName.AsByteStringC());
 }
 CFX_ByteString CXML_Element::GetNamespaceURI(
     const CFX_ByteStringC& qName) const {
diff --git a/core/fxcrt/fxcrt_posix.cpp b/core/fxcrt/fxcrt_posix.cpp
index 2f17e71567..0226313934 100644
--- a/core/fxcrt/fxcrt_posix.cpp
+++ b/core/fxcrt/fxcrt_posix.cpp
@@ -45,7 +45,7 @@ FX_BOOL CFXCRT_FileAccess_Posix::Open(const CFX_ByteStringC& fileName,
 }
 FX_BOOL CFXCRT_FileAccess_Posix::Open(const CFX_WideStringC& fileName,
                                       uint32_t dwMode) {
-  return Open(FX_UTF8Encode(fileName), dwMode);
+  return Open(FX_UTF8Encode(fileName).AsByteStringC(), dwMode);
 }
 void CFXCRT_FileAccess_Posix::Close() {
   if (m_nFD < 0) {
diff --git a/core/fxcrt/include/fx_basic.h b/core/fxcrt/include/fx_basic.h
index feeb6e756d..2ef11beb27 100644
--- a/core/fxcrt/include/fx_basic.h
+++ b/core/fxcrt/include/fx_basic.h
@@ -27,8 +27,8 @@ class CFX_BinaryBuf {
   void Clear();
   void EstimateSize(FX_STRSIZE size, FX_STRSIZE alloc_step = 0);
   void AppendBlock(const void* pBuf, FX_STRSIZE size);
-  void AppendString(const CFX_ByteStringC& str) {
-    AppendBlock(str.GetPtr(), str.GetLength());
+  void AppendString(const CFX_ByteString& str) {
+    AppendBlock(str.c_str(), str.GetLength());
   }
 
   void AppendByte(uint8_t byte) {
@@ -63,6 +63,12 @@ class CFX_ByteTextBuf : public CFX_BinaryBuf {
   CFX_ByteTextBuf& operator<<(int i);
   CFX_ByteTextBuf& operator<<(uint32_t i);
   CFX_ByteTextBuf& operator<<(double f);
+  CFX_ByteTextBuf& operator<<(const FX_CHAR* pStr) {
+    return *this << CFX_ByteStringC(pStr);
+  }
+  CFX_ByteTextBuf& operator<<(const CFX_ByteString& str) {
+    return *this << str.AsByteStringC();
+  }
   CFX_ByteTextBuf& operator<<(const CFX_ByteStringC& lpsz);
   CFX_ByteTextBuf& operator<<(const CFX_ByteTextBuf& buf);
 };
diff --git a/core/fxcrt/include/fx_string.h b/core/fxcrt/include/fx_string.h
index 9aa67845f8..cbf8c4de2f 100644
--- a/core/fxcrt/include/fx_string.h
+++ b/core/fxcrt/include/fx_string.h
@@ -61,8 +61,6 @@ class CFX_ByteStringC {
     m_Length = src.m_Length;
   }
 
-  CFX_ByteStringC(const CFX_ByteString& src);
-
   CFX_ByteStringC& operator=(const FX_CHAR* src) {
     m_Ptr = (const uint8_t*)src;
     m_Length = m_Ptr ? FXSYS_strlen(src) : 0;
@@ -167,12 +165,14 @@ class CFX_ByteString {
   static CFX_ByteString FromUnicode(const CFX_WideString& str);
 
   // Explicit conversion to C-style string.
+  // Note: |this| must outlive the use of the result.
   const FX_CHAR* c_str() const { return m_pData ? m_pData->m_String : ""; }
 
   // Implicit conversion to C-style string -- deprecated.
   operator const FX_CHAR*() const { return m_pData ? m_pData->m_String : ""; }
 
   // Explicit conversion to uint8_t*.
+  // Note: |this| must outlive the use of the result.
   const uint8_t* raw_str() const {
     return m_pData ? reinterpret_cast<const uint8_t*>(m_pData->m_String)
                    : nullptr;
@@ -184,6 +184,12 @@ class CFX_ByteString {
                    : nullptr;
   }
 
+  // Explicit conversion to CFX_ByteStringC.
+  // Note: |this| must outlive the use of the result.
+  CFX_ByteStringC AsByteStringC() const {
+    return CFX_ByteStringC(raw_str(), GetLength());
+  }
+
   FX_STRSIZE GetLength() const { return m_pData ? m_pData->m_nDataLength : 0; }
   bool IsEmpty() const { return !GetLength(); }
 
@@ -330,10 +336,6 @@ class CFX_ByteString {
   friend class fxcrt_ByteStringConcat_Test;
 };
 
-inline CFX_ByteStringC::CFX_ByteStringC(const CFX_ByteString& src) {
-  m_Ptr = (const uint8_t*)src;
-  m_Length = src.GetLength();
-}
 inline CFX_ByteStringC& CFX_ByteStringC::operator=(const CFX_ByteString& src) {
   m_Ptr = (const uint8_t*)src;
   m_Length = src.GetLength();
@@ -373,29 +375,29 @@ inline CFX_ByteString operator+(FX_CHAR ch, const CFX_ByteStringC& str2) {
 }
 inline CFX_ByteString operator+(const CFX_ByteString& str1,
                                 const CFX_ByteString& str2) {
-  return CFX_ByteString(str1, str2);
+  return CFX_ByteString(str1.AsByteStringC(), str2.AsByteStringC());
 }
 inline CFX_ByteString operator+(const CFX_ByteString& str1, FX_CHAR ch) {
-  return CFX_ByteString(str1, CFX_ByteStringC(ch));
+  return CFX_ByteString(str1.AsByteStringC(), CFX_ByteStringC(ch));
 }
 inline CFX_ByteString operator+(FX_CHAR ch, const CFX_ByteString& str2) {
-  return CFX_ByteString(ch, str2);
+  return CFX_ByteString(ch, str2.AsByteStringC());
 }
 inline CFX_ByteString operator+(const CFX_ByteString& str1,
                                 const FX_CHAR* str2) {
-  return CFX_ByteString(str1, str2);
+  return CFX_ByteString(str1.AsByteStringC(), str2);
 }
 inline CFX_ByteString operator+(const FX_CHAR* str1,
                                 const CFX_ByteString& str2) {
-  return CFX_ByteString(str1, str2);
+  return CFX_ByteString(str1, str2.AsByteStringC());
 }
 inline CFX_ByteString operator+(const CFX_ByteString& str1,
                                 const CFX_ByteStringC& str2) {
-  return CFX_ByteString(str1, str2);
+  return CFX_ByteString(str1.AsByteStringC(), str2);
 }
 inline CFX_ByteString operator+(const CFX_ByteStringC& str1,
                                 const CFX_ByteString& str2) {
-  return CFX_ByteString(str1, str2);
+  return CFX_ByteString(str1, str2.AsByteStringC());
 }
 
 class CFX_WideStringC {
@@ -758,7 +760,7 @@ inline CFX_ByteString FX_UTF8Encode(const CFX_WideString& wsStr) {
 
 FX_FLOAT FX_atof(const CFX_ByteStringC& str);
 inline FX_FLOAT FX_atof(const CFX_WideStringC& wsStr) {
-  return FX_atof(FX_UTF8Encode(wsStr.GetPtr(), wsStr.GetLength()));
+  return FX_atof(FX_UTF8Encode(wsStr.GetPtr(), wsStr.GetLength()).c_str());
 }
 void FX_atonum(const CFX_ByteStringC& str, FX_BOOL& bInteger, void* pData);
 FX_STRSIZE FX_ftoa(FX_FLOAT f, FX_CHAR* buf);
diff --git a/core/fxge/ge/fx_ge_ps.cpp b/core/fxge/ge/fx_ge_ps.cpp
index 32f2fce914..ec8f18e774 100644
--- a/core/fxge/ge/fx_ge_ps.cpp
+++ b/core/fxge/ge/fx_ge_ps.cpp
@@ -680,7 +680,7 @@ FX_BOOL CFX_PSRenderer::DrawText(int nChars,
     buf << pCharPos[i].m_OriginX << " " << pCharPos[i].m_OriginY << " m";
     CFX_ByteString hex;
     hex.Format("<%02X>", ps_glyphindex);
-    buf << hex << "Tj\n";
+    buf << hex.AsByteStringC() << "Tj\n";
   }
   buf << "Q\n";
   m_pOutput->OutputPS((const FX_CHAR*)buf.GetBuffer(), buf.GetSize());
diff --git a/core/fxge/win32/fx_win32_device.cpp b/core/fxge/win32/fx_win32_device.cpp
index cb3f331d49..ed57a02c23 100644
--- a/core/fxge/win32/fx_win32_device.cpp
+++ b/core/fxge/win32/fx_win32_device.cpp
@@ -460,7 +460,7 @@ IFX_SystemFontInfo* IFX_SystemFontInfo::CreateDefault(const char** pUnused) {
   if (path_len > 0 && path_len < MAX_PATH) {
     CFX_ByteString fonts_path(windows_path);
     fonts_path += "\\Fonts";
-    pInfoFallback->AddPath(fonts_path);
+    pInfoFallback->AddPath(fonts_path.AsByteStringC());
   }
   return pInfoFallback;
 }