Split fwl/core class pt I.

BUILD.gn

Index: BUILD.gn
diff --git a/BUILD.gn b/BUILD.gn
index f22eeadc72a0f8c8651d8f19feac0e8d7c7ffacb..680fad229334f1fd601dc852b23a2c0dadd200e4 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -1245,6 +1245,8 @@ if (pdf_enable_xfa) {
       "xfa/fwl/core/cfwl_picturebox.h",
       "xfa/fwl/core/cfwl_pushbutton.cpp",
       "xfa/fwl/core/cfwl_pushbutton.h",
+      "xfa/fwl/core/cfwl_sysbtn.cpp",
+      "xfa/fwl/core/cfwl_sysbtn.h",
       "xfa/fwl/core/cfwl_themebackground.h",
       "xfa/fwl/core/cfwl_themepart.h",
       "xfa/fwl/core/cfwl_themetext.h",
@@ -1277,7 +1279,6 @@ if (pdf_enable_xfa) {
       "xfa/fwl/core/ifwl_comboedit.h",
       "xfa/fwl/core/ifwl_combolist.cpp",
       "xfa/fwl/core/ifwl_combolist.h",
-      "xfa/fwl/core/ifwl_dataprovider.h",
       "xfa/fwl/core/ifwl_datetimeedit.cpp",
       "xfa/fwl/core/ifwl_datetimeedit.h",
       "xfa/fwl/core/ifwl_datetimepicker.cpp",
@@ -1303,6 +1304,8 @@ if (pdf_enable_xfa) {
       "xfa/fwl/core/ifwl_themeprovider.h",
       "xfa/fwl/core/ifwl_timer.cpp",
       "xfa/fwl/core/ifwl_timer.h",
+      "xfa/fwl/core/ifwl_timerinfo.cpp",
+      "xfa/fwl/core/ifwl_timerinfo.h",
       "xfa/fwl/core/ifwl_tooltip.cpp",
       "xfa/fwl/core/ifwl_tooltip.h",
       "xfa/fwl/core/ifwl_widget.cpp",