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

xfa/fxfa/app/xfa_checksum.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/include/xfa_checksum.h"
 
 #include "core/fdrm/crypto/include/fx_crypt.h"
 #include "xfa/fgas/crt/fgas_algorithm.h"
@@ skipping 116 matching lines @@
 
 CXFA_ChecksumContext::CXFA_ChecksumContext()
     : m_pSAXReader(NULL), m_pByteContext(NULL) {}
 CXFA_ChecksumContext::~CXFA_ChecksumContext() {
   FinishChecksum();
 }
 FX_BOOL CXFA_ChecksumContext::StartChecksum() {
   FinishChecksum();
   m_pByteContext = FX_Alloc(uint8_t, 128);
   CRYPT_SHA1Start(m_pByteContext);
-  m_bsChecksum.Empty();
+  m_bsChecksum.clear();
   m_pSAXReader = FX_SAXReader_Create();
   return m_pSAXReader != NULL;
 }
 FX_BOOL CXFA_ChecksumContext::UpdateChecksum(IFX_FileRead* pSrcFile,
                                              FX_FILESIZE offset,
                                              size_t size) {
   if (m_pSAXReader == NULL) {
     return FALSE;
   }
   if (pSrcFile == NULL) {
@@ skipping 31 matching lines @@
   }
 }
 void CXFA_ChecksumContext::GetChecksum(CFX_ByteString& bsChecksum) {
   bsChecksum = m_bsChecksum;
 }
 void CXFA_ChecksumContext::Update(const CFX_ByteStringC& bsText) {
   if (m_pByteContext) {
     CRYPT_SHA1Update(m_pByteContext, bsText.raw_str(), bsText.GetLength());
   }
 }