Change IFWL_Widget to store a single delegate.

xfa/fxfa/app/xfa_ffpushbutton.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_FXFA_APP_XFA_FFPUSHBUTTON_H_
 #define XFA_FXFA_APP_XFA_FFPUSHBUTTON_H_
 
 #include "xfa/fxfa/app/xfa_fffield.h"
@@ skipping 11 matching lines @@
   ~CXFA_FFPushButton() override;
 
   // CXFA_FFField
   void RenderWidget(CFX_Graphics* pGS,
                     CFX_Matrix* pMatrix,
                     uint32_t dwStatus) override;
   FX_BOOL LoadWidget() override;
   void UnloadWidget() override;
   FX_BOOL PerformLayout() override;
   void UpdateWidgetProperty() override;
-  void OnProcessMessage(CFWL_Message* pMessage) override;
-  void OnProcessEvent(CFWL_Event* pEvent) override;
-  void OnDrawWidget(CFX_Graphics* pGraphics,
-                    const CFX_Matrix* pMatrix = nullptr) override;
+
+  FX_FLOAT GetLineWidth();
 
  protected:
   void LoadHighlightCaption();
   void LayoutHighlightCaption();
   void RenderHighlightCaption(CFX_Graphics* pGS, CFX_Matrix* pMatrix = nullptr);
-  FX_FLOAT GetLineWidth();
   FX_ARGB GetLineColor();
   FX_ARGB GetFillColor();
 
   CXFA_TextLayout* m_pRolloverTextLayout;
   CXFA_TextLayout* m_pDownTextLayout;
   CXFA_TextProvider* m_pDownProvider;
   CXFA_TextProvider* m_pRollProvider;
-  IFWL_WidgetDelegate* m_pOldDelegate;
 };
 
 #endif  // XFA_FXFA_APP_XFA_FFPUSHBUTTON_H_