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

xfa/fxfa/app/xfa_fwltheme.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/app/xfa_fwltheme.h"
 
 #include "xfa/fde/tto/fde_textout.h"
 #include "xfa/fgas/crt/fgas_codepage.h"
@@ skipping 250 matching lines @@
       return &m_SizeAboveBelow;
     } break;
     default:
       break;
   }
   if (pThemePart->m_pWidget->GetClassID() == FWL_CLASSHASH_MonthCalendar &&
       dwCapacity >= FWL_MCCAPACITY_Sun && dwCapacity <= FWL_MCCAPACITY_Today) {
     if (CXFA_FFWidget* pWidget =
             XFA_ThemeGetOuterWidget(pThemePart->m_pWidget)) {
       IXFA_AppProvider* pAppProvider = pWidget->GetAppProvider();
-      m_wsResource.Empty();
+      m_wsResource.clear();
       pAppProvider->LoadString(
           XFA_IDS_StringWeekDay_Sun + dwCapacity - FWL_WGTCAPACITY_MAX - 5,
           m_wsResource);
       if (!m_wsResource.IsEmpty()) {
         return &m_wsResource;
       }
     }
   }
   return GetTheme(pThemePart->m_pWidget)->GetCapacity(pThemePart, dwCapacity);
 }
@@ skipping 141 matching lines @@
       }
     }
     CFX_Color crLine(cr);
     pParams->m_pGraphics->SetStrokeColor(&crLine);
     pParams->m_pGraphics->SetLineWidth(fWidth);
     pParams->m_pGraphics->StrokePath(pParams->m_pPath, &pParams->m_matrix);
     return TRUE;
   }
   return CFWL_EditTP::DrawBackground(pParams);
 }