Change IFWL_Widget to store a single delegate.

xfa/fxfa/app/xfa_ffpushbutton.h

Index: xfa/fxfa/app/xfa_ffpushbutton.h
diff --git a/xfa/fxfa/app/xfa_ffpushbutton.h b/xfa/fxfa/app/xfa_ffpushbutton.h
index e7c9bd774692d9b35d36a9b5cd83861db500610d..ecbb05e6ccaaeb611f81215e333232f3ee8965db 100644
--- a/xfa/fxfa/app/xfa_ffpushbutton.h
+++ b/xfa/fxfa/app/xfa_ffpushbutton.h
@@ -29,16 +29,13 @@ class CXFA_FFPushButton : public CXFA_FFField {
   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();
 
@@ -46,7 +43,6 @@ class CXFA_FFPushButton : public CXFA_FFField {
   CXFA_TextLayout* m_pDownTextLayout;
   CXFA_TextProvider* m_pDownProvider;
   CXFA_TextProvider* m_pRollProvider;
-  IFWL_WidgetDelegate* m_pOldDelegate;
 };
 
 #endif  // XFA_FXFA_APP_XFA_FFPUSHBUTTON_H_