More master side changes for convergence with XFA.

fpdfsdk/include/fsdk_define.h

Index: fpdfsdk/include/fsdk_define.h
diff --git a/fpdfsdk/include/fsdk_define.h b/fpdfsdk/include/fsdk_define.h
index 37788c3ff70a1129e5daa3f1dbdb43f39897163d..6e3c7189485bb46a4a15121762c5f1a05bab0c42 100644
--- a/fpdfsdk/include/fsdk_define.h
+++ b/fpdfsdk/include/fsdk_define.h
@@ -52,8 +52,10 @@ class CPDF_CustomAccess final : public IFX_FileRead {
   FPDF_FILEACCESS m_FileAccess;
 };
 
-// Conversions from FPDF_ types.
+// Conversions to/from FPDF_ types.
 CPDF_Document* CPDFDocumentFromFPDFDocument(FPDF_DOCUMENT doc);
+FPDF_DOCUMENT FPDFDocumentFromCPDFDocument(CPDF_Document* doc);
+
 CPDF_Page* CPDFPageFromFPDFPage(FPDF_PAGE page);
 
 void DropContext(void* data);