Remove CLASSHASH defines in favour of an enum class.

xfa/fwl/theme/cfwl_pictureboxtp.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/fwl/theme/cfwl_pictureboxtp.h"
 
 #include "xfa/fwl/basewidget/ifwl_picturebox.h"
 #include "xfa/fwl/core/cfwl_themebackground.h"
 #include "xfa/fwl/core/ifwl_widget.h"
 
 CFWL_PictureBoxTP::CFWL_PictureBoxTP() {}
 
 CFWL_PictureBoxTP::~CFWL_PictureBoxTP() {}
 
-FX_BOOL CFWL_PictureBoxTP::IsValidWidget(IFWL_Widget* pWidget) {
-  if (!pWidget)
-    return FALSE;
-  return pWidget->GetClassID() == FWL_CLASSHASH_PictureBox;
+bool CFWL_PictureBoxTP::IsValidWidget(IFWL_Widget* pWidget) {
+  return pWidget && pWidget->GetClassID() == FWL_Type::PictureBox;
 }
+
 FX_BOOL CFWL_PictureBoxTP::DrawBackground(CFWL_ThemeBackground* pParams) {
   if (!pParams)
     return FALSE;
+
   switch (pParams->m_iPart) {
     case CFWL_Part::Border: {
       DrawBorder(pParams->m_pGraphics, &pParams->m_rtPart, &pParams->m_matrix);
       break;
     }
     case CFWL_Part::Edge: {
       DrawEdge(pParams->m_pGraphics, pParams->m_pWidget->GetStyles(),
                &pParams->m_rtPart, &pParams->m_matrix);
       break;
     }
-    default: {}
+    default:
+      break;
   }
   return TRUE;
 }