Merge the CFWL_*Imp classes into the IFWL_* classes.

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() 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_