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

xfa/fxfa/parser/xfa_object_imp.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 "xfa/fxfa/parser/xfa_object.h"
 
 #include "core/fxcrt/include/fx_ext.h"
 #include "xfa/fde/xml/fde_xml_imp.h"
@@ skipping 4450 matching lines @@
       return ToNode(m_pDocument->GetXFAObject(XFA_HASHCODE_ConnectionSet));
     case XFA_XDPPACKET_SourceSet:
       return ToNode(m_pDocument->GetXFAObject(XFA_HASHCODE_SourceSet));
     case XFA_XDPPACKET_Xdc:
       return ToNode(m_pDocument->GetXFAObject(XFA_HASHCODE_Xdc));
     default:
       return this;
   }
 }
 FX_BOOL CXFA_Node::TryNamespace(CFX_WideString& wsNamespace) {
-  wsNamespace.Empty();
+  wsNamespace.clear();
   if (GetObjectType() == XFA_OBJECTTYPE_ModelNode ||
       GetClassID() == XFA_ELEMENT_Packet) {
     CFDE_XMLNode* pXMLNode = GetXMLMappingNode();
     if (!pXMLNode || pXMLNode->GetType() != FDE_XMLNODE_Element) {
       return FALSE;
     }
     static_cast<CFDE_XMLElement*>(pXMLNode)->GetNamespaceURI(wsNamespace);
     return TRUE;
   } else if (GetPacketID() == XFA_XDPPACKET_Datasets) {
     CFDE_XMLNode* pXMLNode = GetXMLMappingNode();
@@ skipping 928 matching lines @@
   return m_pAttachNode->InsertChild(pNewNode, pBeforeNode);
 }
 FX_BOOL CXFA_AttachNodeList::Remove(CXFA_Node* pNode) {
   return m_pAttachNode->RemoveChild(pNode);
 }
 CXFA_Node* CXFA_AttachNodeList::Item(int32_t iIndex) {
   return m_pAttachNode->GetChild(
       iIndex, XFA_ELEMENT_UNKNOWN,
       m_pAttachNode->GetClassID() == XFA_ELEMENT_Subform);
 }