Revert "Make CFX_WideString::LockBuffer() completely unused."

core/src/fxcrt/fx_basic_bstring.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 "../../include/fxcrt/fx_basic.h"
 #include "../../../third_party/base/numerics/safe_math.h"
 
 static int _Buffer_itoa(char* buf, int i, FX_DWORD flags)
@@ skipping 323 matching lines @@
         nNewLength = (FX_STRSIZE)FXSYS_strlen((FX_LPCSTR)m_pData->m_String);
     }
     if (nNewLength == 0) {
         Empty();
         return;
     }
     FXSYS_assert(nNewLength <= m_pData->m_nAllocLength);
     m_pData->m_nDataLength = nNewLength;
     m_pData->m_String[nNewLength] = 0;
 }
+FX_LPSTR CFX_ByteString::LockBuffer()
+{
+    if (m_pData == NULL) {
+        return NULL;
+    }
+    FX_LPSTR lpsz = GetBuffer(0);
+    m_pData->m_nRefs = -1;
+    return lpsz;
+}
 void CFX_ByteString::Reserve(FX_STRSIZE len)
 {
     GetBuffer(len);
     ReleaseBuffer(GetLength());
 }
 FX_LPSTR CFX_ByteString::GetBuffer(FX_STRSIZE nMinBufLength)
 {
     if (m_pData == NULL && nMinBufLength == 0) {
         return NULL;
     }
@@ skipping 767 matching lines @@
         scale /= 10;
     }
     return buf_size;
 }
 CFX_ByteString CFX_ByteString::FormatFloat(FX_FLOAT d, int precision)
 {
     FX_CHAR buf[32];
     FX_STRSIZE len = FX_ftoa(d, buf);
     return CFX_ByteString(buf, len);
 }