Rename both As{Byte,Wide}StringC() helpers to AsStringC().

testing/libfuzzer/pdf_fm2js_fuzzer.cc

 // Copyright 2016 The 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.
 
 #include <cstddef>
 #include <cstdint>
 
 #include "core/fxcrt/include/fx_basic.h"
 #include "core/fxcrt/include/fx_string.h"
 #include "xfa/fxfa/fm2js/xfa_program.h"
 
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
   if (size > std::numeric_limits<FX_STRSIZE>::max())
     return 0;
 
   CFX_WideString input = CFX_WideString::FromUTF8(
       CFX_ByteStringC(data, static_cast<FX_STRSIZE>(size)));
   CXFA_FMProgram program;
-  if (program.Init(input.AsWideStringC()) || program.ParseProgram())
+  if (program.Init(input.AsStringC()) || program.ParseProgram())
     return 0;
 
   CFX_WideTextBuf js;
   program.TranslateProgram(js);
   return 0;
 }