Make creation of CPDFSDK_Document clearer

fpdfsdk/fpdfxfa/fpdfxfa_doc.cpp

Index: fpdfsdk/fpdfxfa/fpdfxfa_doc.cpp
diff --git a/fpdfsdk/fpdfxfa/fpdfxfa_doc.cpp b/fpdfsdk/fpdfxfa/fpdfxfa_doc.cpp
index 8db16bf4e952904b163efefa66504d6938b8d532..2d74c02d23b3cc41f8f9f1fbac7e16a2d09c41df 100644
--- a/fpdfsdk/fpdfxfa/fpdfxfa_doc.cpp
+++ b/fpdfsdk/fpdfxfa/fpdfxfa_doc.cpp
@@ -191,11 +191,8 @@ void CPDFXFA_Document::RemovePage(CPDFXFA_Page* page) {
   m_XFAPageList.SetAt(page->GetPageIndex(), nullptr);
 }
 
-CPDFSDK_Document* CPDFXFA_Document::GetSDKDocument(
-    CPDFSDK_Environment* pFormFillEnv) {
-  if (!m_pSDKDoc && pFormFillEnv)
-    m_pSDKDoc.reset(new CPDFSDK_Document(this, pFormFillEnv));
-  return m_pSDKDoc.get();
+void CPDFXFA_Document::SetSDKDoc(std::unique_ptr<CPDFSDK_Document> pSDKDoc) {

[dsinclair, 2016/09/22 14:50:10]

The one difference between this and the old code, in the old world if
FPDFDOC_InitFormFillEnvironment was called twice, we'd have the same
CPDFSDK_Document. In this world, we'll have a new one.

[Tom Sepez, 2016/09/22 17:02:23]

Acknowledged.

[Tom Sepez, 2016/09/22 17:04:42]

Actually, this scares me.  who own the CPDFSKD_Document?  The XFA document or th
CPDFSDK_Environment?

[dsinclair, 2016/09/22 17:32:12]

Depends. In XFA it's owned by CPDFXFA_Document. In non-XFA, it's owned by the
CPDFSDK_Environment.  I changed the Init code so that this shouldn't happen,
basically if the CPDFXFA_Document has been init'd already then we just return
the previously created Environment.

+  m_pSDKDoc.reset(pSDKDoc.release());
 }
 
 void CPDFXFA_Document::ClearChangeMark() {