Rename m_pApp to m_pEnv

fpdfsdk/formfiller/cffl_checkbox.cpp

Index: fpdfsdk/formfiller/cffl_checkbox.cpp
diff --git a/fpdfsdk/formfiller/cffl_checkbox.cpp b/fpdfsdk/formfiller/cffl_checkbox.cpp
index 9b9245d410ac4add7496ef0ce801e72861079244..ef1bf18ea659151456a4ce80587f4cef2790e0f0 100644
--- a/fpdfsdk/formfiller/cffl_checkbox.cpp
+++ b/fpdfsdk/formfiller/cffl_checkbox.cpp
@@ -42,7 +42,7 @@ FX_BOOL CFFL_CheckBox::OnChar(CPDFSDK_Annot* pAnnot,
   switch (nChar) {
     case FWL_VKEY_Return:
     case FWL_VKEY_Space: {
-      CFFL_IFormFiller* pIFormFiller = m_pApp->GetIFormFiller();
+      CFFL_IFormFiller* pIFormFiller = m_pEnv->GetIFormFiller();
       ASSERT(pIFormFiller);
 
       CPDFSDK_PageView* pPageView = pAnnot->GetPageView();