Make down-conversion explicit from CFX_ByteString to CFX_ByteStringC.

fpdfsdk/pdfwindow/PWL_Label.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 "fpdfsdk/pdfwindow/PWL_Label.h"
 #include "fpdfsdk/pdfwindow/PWL_Utils.h"
 #include "fpdfsdk/pdfwindow/PWL_Wnd.h"
 
@@ skipping 100 matching lines @@
   m_pEdit->SetCharSpace(fCharSpace);
 }
 
 CFX_FloatRect CPWL_Label::GetContentRect() const {
   return m_pEdit->GetContentRect();
 }
 
 void CPWL_Label::GetThisAppearanceStream(CFX_ByteTextBuf& sAppStream) {
   CPWL_Wnd::GetThisAppearanceStream(sAppStream);
 
-  sAppStream << GetTextAppearanceStream(CFX_FloatPoint(0.0f, 0.0f));
+  sAppStream << GetTextAppearanceStream(CFX_FloatPoint(0.0f, 0.0f))
+                    .AsByteStringC();
 }
 
 CFX_ByteString CPWL_Label::GetTextAppearanceStream(
     const CFX_FloatPoint& ptOffset) const {
   CFX_ByteTextBuf sRet;
   CFX_ByteString sEdit = CPWL_Utils::GetEditAppStream(m_pEdit, ptOffset);
 
   if (sEdit.GetLength() > 0) {
-    sRet << "BT\n" << CPWL_Utils::GetColorAppStream(GetTextColor()) << sEdit
-         << "ET\n";
+    sRet << "BT\n"
+         << CPWL_Utils::GetColorAppStream(GetTextColor()).AsByteStringC()
+         << sEdit.AsByteStringC() << "ET\n";
   }
 
   return sRet.GetByteString();
 }
 
 CFX_WideString CPWL_Label::GetText() const {
   return m_pEdit->GetText();
 }
 
 void CPWL_Label::SetLimitChar(int32_t nLimitChar) {
   m_pEdit->SetLimitChar(nLimitChar);
 }
 
 int32_t CPWL_Label::GetTotalWords() {
   if (m_pEdit)
     return m_pEdit->GetTotalWords();
 
   return 0;
 }