Make the CPDFXFA_App non-global

fpdfsdk/fpdfdoc_unittest.cpp

Index: fpdfsdk/fpdfdoc_unittest.cpp
diff --git a/fpdfsdk/fpdfdoc_unittest.cpp b/fpdfsdk/fpdfdoc_unittest.cpp
index fc85404dbaee30019f5a694e0be1bc1c27ea0e9d..45beacfdd052f42e5d91b903eafebfd669d55fe4 100644
--- a/fpdfsdk/fpdfdoc_unittest.cpp
+++ b/fpdfsdk/fpdfdoc_unittest.cpp
@@ -35,8 +35,7 @@ class CPDF_TestDocument : public CPDF_Document {
 class CPDF_TestXFADocument : public CPDFXFA_Document {
  public:
   CPDF_TestXFADocument()
-      : CPDFXFA_Document(pdfium::MakeUnique<CPDF_TestDocument>(),
-                         CPDFXFA_App::GetInstance()) {}
+      : CPDFXFA_Document(pdfium::MakeUnique<CPDF_TestDocument>()) {}
 
   void SetRoot(CPDF_Dictionary* root) {
     reinterpret_cast<CPDF_TestDocument*>(GetPDFDoc())->SetRoot(root);