Make CFX_WideString::FromUTF8() take a CFX_ByteStringC argument.

core/fxcrt/fx_basic_wstring.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 <stddef.h>
 
 #include <algorithm>
 #include <cctype>
@@ skipping 354 matching lines @@
   return FromCodePage(str, 0);
 }
 
 // static
 CFX_WideString CFX_WideString::FromCodePage(const CFX_ByteString& str,
                                             uint16_t codepage) {
   return CFX_CharMap::GetWideString(codepage, str);
 }
 
 // static
-CFX_WideString CFX_WideString::FromUTF8(const char* str, FX_STRSIZE len) {
-  if (!str || 0 == len) {
+CFX_WideString CFX_WideString::FromUTF8(const CFX_ByteStringC& str) {
+  if (str.IsEmpty())
     return CFX_WideString();
-  }
 
   CFX_UTF8Decoder decoder;
-  for (FX_STRSIZE i = 0; i < len; i++) {
+  for (FX_STRSIZE i = 0; i < str.GetLength(); i++) {
     decoder.Input(str[i]);
   }
   return decoder.GetResult();
 }
 
 // static
 CFX_WideString CFX_WideString::FromUTF16LE(const unsigned short* wstr,
                                            FX_STRSIZE wlen) {
   if (!wstr || 0 == wlen) {
     return CFX_WideString();
@@ skipping 642 matching lines @@
   int dest_len =
       FXSYS_MultiByteToWideChar(codepage, 0, bstr, src_len, nullptr, 0);
   CFX_WideString wstr;
   if (dest_len) {
     FX_WCHAR* dest_buf = wstr.GetBuffer(dest_len);
     FXSYS_MultiByteToWideChar(codepage, 0, bstr, src_len, dest_buf, dest_len);
     wstr.ReleaseBuffer(dest_len);
   }
   return wstr;
 }