Get rid of NULLs in xfa/

xfa/fxfa/app/xfa_fffield.h

Index: xfa/fxfa/app/xfa_fffield.h
diff --git a/xfa/fxfa/app/xfa_fffield.h b/xfa/fxfa/app/xfa_fffield.h
index fd6661dea237f3ab3f70af3a4d74d395ce3ab268..92e9cadcc4a7b2932aa5b4b74b79147e46ca3afc 100644
--- a/xfa/fxfa/app/xfa_fffield.h
+++ b/xfa/fxfa/app/xfa_fffield.h
@@ -24,7 +24,7 @@ class CXFA_FFField : public CXFA_FFWidget, public IFWL_WidgetDelegate {
                           uint32_t dwStatus,
                           FX_BOOL bDrawFocus = FALSE);
   virtual void RenderWidget(CFX_Graphics* pGS,
-                            CFX_Matrix* pMatrix = NULL,
+                            CFX_Matrix* pMatrix = nullptr,
                             uint32_t dwStatus = 0,
                             int32_t iRotate = 0);
   virtual FX_BOOL IsLoaded();
@@ -62,7 +62,7 @@ class CXFA_FFField : public CXFA_FFWidget, public IFWL_WidgetDelegate {
   CFWL_Widget* GetNormalWidget() { return m_pNormalWidget; }
   void FWLToClient(FX_FLOAT& fx, FX_FLOAT& fy);
   void LayoutCaption();
-  void RenderCaption(CFX_Graphics* pGS, CFX_Matrix* pMatrix = NULL);
+  void RenderCaption(CFX_Graphics* pGS, CFX_Matrix* pMatrix = nullptr);
 
   int32_t CalculateOverride();
   int32_t CalculateWidgetAcc(CXFA_WidgetAcc* pAcc);
@@ -88,7 +88,7 @@ class CXFA_FFField : public CXFA_FFWidget, public IFWL_WidgetDelegate {
   virtual void OnProcessMessage(CFWL_Message* pMessage);
   virtual void OnProcessEvent(CFWL_Event* pEvent);
   virtual void OnDrawWidget(CFX_Graphics* pGraphics,
-                            const CFX_Matrix* pMatrix = NULL);
+                            const CFX_Matrix* pMatrix = nullptr);
 
  protected:
   CFWL_Widget* m_pNormalWidget;