Make CFX_ByteString(const CFX_ByteStringC&) explicit.

core/fxcrt/fx_basic_buffer.cpp

Index: core/fxcrt/fx_basic_buffer.cpp
diff --git a/core/fxcrt/fx_basic_buffer.cpp b/core/fxcrt/fx_basic_buffer.cpp
index 6008a00b40dc3bfee20125f95977710c674b19ce..2762497e5cf987392e5dc17fac698f6c6933c1b3 100644
--- a/core/fxcrt/fx_basic_buffer.cpp
+++ b/core/fxcrt/fx_basic_buffer.cpp
@@ -100,10 +100,6 @@ void CFX_BinaryBuf::InsertBlock(FX_STRSIZE pos,
   m_DataSize += size;
 }
 
-CFX_ByteStringC CFX_ByteTextBuf::AsStringC() const {
-  return CFX_ByteStringC(m_pBuffer.get(), m_DataSize);
-}
-
 CFX_ByteTextBuf& CFX_ByteTextBuf::operator<<(const CFX_ByteStringC& lpsz) {
   AppendBlock(lpsz.raw_str(), lpsz.GetLength());
   return *this;