Remove CLASSHASH defines in favour of an enum class.

xfa/fwl/basewidget/fwl_formproxyimp.h

 // 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
 
 #ifndef XFA_FWL_BASEWIDGET_FWL_FORMPROXYIMP_H_
 #define XFA_FWL_BASEWIDGET_FWL_FORMPROXYIMP_H_
 
 #include "xfa/fwl/core/fwl_formimp.h"
 #include "xfa/fwl/core/fwl_widgetimp.h"
 
 class CFWL_WidgetImpProperties;
 class CFWL_FormProxyImpDelegate;
 
 class CFWL_FormProxyImp : public CFWL_FormImp {
  public:
   CFWL_FormProxyImp(const CFWL_WidgetImpProperties& properties,
                     IFWL_Widget* pOuter);
-  ~CFWL_FormProxyImp();
-  virtual FWL_Error GetClassName(CFX_WideString& wsClass) const;
-  virtual uint32_t GetClassID() const;
-  virtual FX_BOOL IsInstance(const CFX_WideStringC& wsClass) const;
-  virtual FWL_Error Initialize();
-  virtual FWL_Error Finalize();
-  virtual FWL_Error Update();
-  virtual FWL_Error DrawWidget(CFX_Graphics* pGraphics,
-                               const CFX_Matrix* pMatrix = NULL);
+  ~CFWL_FormProxyImp() override;
+
+  // CFWL_WidgetImp
+  FWL_Error GetClassName(CFX_WideString& wsClass) const override;
+  FWL_Type GetClassID() const override;
+  FX_BOOL IsInstance(const CFX_WideStringC& wsClass) const override;
+  FWL_Error Initialize() override;
+  FWL_Error Finalize() override;
+  FWL_Error Update() override;
+  FWL_Error DrawWidget(CFX_Graphics* pGraphics,
+                       const CFX_Matrix* pMatrix = nullptr) override;
 
  protected:
   friend class CFWL_FormProxyImpDelegate;
 };
+
 class CFWL_FormProxyImpDelegate : public CFWL_WidgetImpDelegate {
  public:
   CFWL_FormProxyImpDelegate(CFWL_FormProxyImp* pOwner);
   void OnProcessMessage(CFWL_Message* pMessage) override;
 
  protected:
   CFWL_FormProxyImp* m_pOwner;
 };
 
 #endif  // XFA_FWL_BASEWIDGET_FWL_FORMPROXYIMP_H_