Replace calls to deprecated CFX_{Wide,Byte}String::Empty()

fpdfsdk/pdfwindow/PWL_Edit.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_Edit.h"
 
 #include <vector>
 
@@ skipping 28 matching lines @@
   CFX_WideString swText = csText;
 
   if (HasFlag(PES_RICH)) {
     CFX_ByteString sValue = CFX_ByteString::FromUnicode(swText);
 
     if (CXML_Element* pXML =
             CXML_Element::Parse(sValue.c_str(), sValue.GetLength())) {
       int32_t nCount = pXML->CountChildren();
       FX_BOOL bFirst = TRUE;
 
-      swText.Empty();
+      swText.clear();
 
       for (int32_t i = 0; i < nCount; i++) {
         if (CXML_Element* pSubElement = pXML->GetElement(i)) {
           CFX_ByteString tag = pSubElement->GetTagName();
           if (tag.EqualNoCase("p")) {
             int nChild = pSubElement->CountChildren();
             CFX_WideString swSection;
             for (int32_t j = 0; j < nChild; j++) {
               swSection += pSubElement->GetContent(j);
             }
@@ skipping 1078 matching lines @@
 }
 
 void CPWL_Edit::GeneratePageObjects(CPDF_PageObjectHolder* pObjectHolder,
                                     const CFX_FloatPoint& ptOffset) {
   CFX_ArrayTemplate<CPDF_TextObject*> ObjArray;
   IFX_Edit::GeneratePageObjects(
       pObjectHolder, m_pEdit, ptOffset, NULL,
       CPWL_Utils::PWLColorToFXColor(GetTextColor(), GetTransparency()),
       ObjArray);
 }