Remove argument from Annot_OnChangeFocus().

Follow-on from https://pdfium-review.googlesource.com/c/pdfium/+/85352

In turn, remove call with null argument, since we know it will be
a no-op.

Change-Id: I5211b3052d5cf89e499aa675c586bb7d82532ca5
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/85353
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Tom Sepez <tsepez@chromium.org>
diff --git a/fpdfsdk/cpdfsdk_formfillenvironment.cpp b/fpdfsdk/cpdfsdk_formfillenvironment.cpp
index 1326804..1822101 100644
--- a/fpdfsdk/cpdfsdk_formfillenvironment.cpp
+++ b/fpdfsdk/cpdfsdk_formfillenvironment.cpp
@@ -762,14 +762,14 @@
     return false;
 
 #ifdef PDF_ENABLE_XFA
-  ObservedPtr<CPDFSDK_Annot> pLastFocusAnnot(m_pFocusAnnot.Get());
-  if (!pAnnotHandler->Annot_OnChangeFocus(pAnnot, &pLastFocusAnnot))
+  if (!pAnnotHandler->Annot_OnChangeFocus(pAnnot))
     return false;
 
   // |pAnnot| may be destroyed in |Annot_OnChangeFocus|.
   if (!pAnnot->HasObservable())
     return false;
 #endif  // PDF_ENABLE_XFA
+
   if (!pAnnotHandler->Annot_OnSetFocus(pAnnot, {}))
     return false;
   if (m_pFocusAnnot)
@@ -791,12 +791,6 @@
   ObservedPtr<CPDFSDK_Annot> pFocusAnnot(m_pFocusAnnot.Get());
   m_pFocusAnnot.Reset();
 
-#ifdef PDF_ENABLE_XFA
-  ObservedPtr<CPDFSDK_Annot> pNull;
-  if (!pAnnotHandler->Annot_OnChangeFocus(&pNull, &pFocusAnnot))
-    return false;
-#endif  // PDF_ENABLE_XFA
-
   if (!pAnnotHandler->Annot_OnKillFocus(&pFocusAnnot, nFlag)) {
     m_pFocusAnnot.Reset(pFocusAnnot.Get());
     return false;