Split xfa_document_serialize into class files

BUILD.gn

 # Copyright 2016 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build_overrides/v8.gni")
 import("//testing/test.gni")
 import("pdfium.gni")
 
 config("pdfium_common_config") {
   cflags = []
@@ skipping 1352 matching lines @@
       "xfa/fxfa/parser/cxfa_calculate.h",
       "xfa/fxfa/parser/cxfa_caption.cpp",
       "xfa/fxfa/parser/cxfa_caption.h",
       "xfa/fxfa/parser/cxfa_containerlayoutitem.cpp",
       "xfa/fxfa/parser/cxfa_containerlayoutitem.h",
       "xfa/fxfa/parser/cxfa_contentlayoutitem.cpp",
       "xfa/fxfa/parser/cxfa_contentlayoutitem.h",
       "xfa/fxfa/parser/cxfa_corner.h",
       "xfa/fxfa/parser/cxfa_data.cpp",
       "xfa/fxfa/parser/cxfa_data.h",
+      "xfa/fxfa/parser/cxfa_dataexporter.cpp",
+      "xfa/fxfa/parser/cxfa_dataexporter.h",
+      "xfa/fxfa/parser/cxfa_dataimporter.cpp",
+      "xfa/fxfa/parser/cxfa_dataimporter.h",
       "xfa/fxfa/parser/cxfa_document.cpp",
       "xfa/fxfa/parser/cxfa_document.h",
       "xfa/fxfa/parser/cxfa_document_parser.cpp",
       "xfa/fxfa/parser/cxfa_document_parser.h",
       "xfa/fxfa/parser/cxfa_edge.h",
       "xfa/fxfa/parser/cxfa_event.cpp",
       "xfa/fxfa/parser/cxfa_event.h",
       "xfa/fxfa/parser/cxfa_exdata.cpp",
       "xfa/fxfa/parser/cxfa_exdata.h",
       "xfa/fxfa/parser/cxfa_fill.cpp",
@@ skipping 55 matching lines @@
       "xfa/fxfa/parser/xfa_basic_data.cpp",
       "xfa/fxfa/parser/xfa_basic_data.h",
       "xfa/fxfa/parser/xfa_basic_data_attributes.cpp",
       "xfa/fxfa/parser/xfa_basic_data_element_attributes.cpp",
       "xfa/fxfa/parser/xfa_basic_data_element_properties.cpp",
       "xfa/fxfa/parser/xfa_basic_data_element_script.cpp",
       "xfa/fxfa/parser/xfa_basic_data_enum.cpp",
       "xfa/fxfa/parser/xfa_basic_data_packets.cpp",
       "xfa/fxfa/parser/xfa_document_datamerger_imp.cpp",
       "xfa/fxfa/parser/xfa_document_datamerger_imp.h",
-      "xfa/fxfa/parser/xfa_document_serialize.cpp",
-      "xfa/fxfa/parser/xfa_document_serialize.h",
       "xfa/fxfa/parser/xfa_layout_appadapter.cpp",
       "xfa/fxfa/parser/xfa_layout_appadapter.h",
       "xfa/fxfa/parser/xfa_layout_itemlayout.cpp",
       "xfa/fxfa/parser/xfa_layout_itemlayout.h",
       "xfa/fxfa/parser/xfa_layout_pagemgr_new.cpp",
       "xfa/fxfa/parser/xfa_layout_pagemgr_new.h",
       "xfa/fxfa/parser/xfa_locale.cpp",
       "xfa/fxfa/parser/xfa_locale.h",
       "xfa/fxfa/parser/xfa_localemgr.cpp",
       "xfa/fxfa/parser/xfa_localemgr.h",
@@ skipping 140 matching lines @@
 }
 
 if (pdf_is_standalone) {
   source_set("samples") {
     testonly = true
     deps = [
       "//samples",
     ]
   }
 }