Merge the CFWL_*Imp classes into the IFWL_* classes.

xfa/fwl/lightwidget/cfwl_combobox.h

Index: xfa/fwl/lightwidget/cfwl_combobox.h
diff --git a/xfa/fwl/lightwidget/cfwl_combobox.h b/xfa/fwl/lightwidget/cfwl_combobox.h
index bbcec3bb8b0d3b51690ce499f13625ab6f661da2..b6dee570cbf9fbb3eb4615e89c2feaecb981b422 100644
--- a/xfa/fwl/lightwidget/cfwl_combobox.h
+++ b/xfa/fwl/lightwidget/cfwl_combobox.h
@@ -10,7 +10,7 @@
 #include <memory>
 #include <vector>
 
-#include "xfa/fwl/basewidget/ifwl_combobox.h"
+#include "xfa/fwl/core/ifwl_combobox.h"
 #include "xfa/fwl/lightwidget/cfwl_widget.h"
 
 class CFWL_WidgetProperties;
@@ -82,8 +82,8 @@ class CFWL_ComboBox : public CFWL_Widget {
                          CFX_WideString& wsCaption) override;
 
     // IFWL_ListBoxDP
-    int32_t CountItems(IFWL_Widget* pWidget) override;
-    IFWL_ListItem* GetItem(IFWL_Widget* pWidget, int32_t nIndex) override;
+    int32_t CountItems(const IFWL_Widget* pWidget) override;
+    IFWL_ListItem* GetItem(const IFWL_Widget* pWidget, int32_t nIndex) override;
     int32_t GetItemIndex(IFWL_Widget* pWidget, IFWL_ListItem* pItem) override;
     FX_BOOL SetItemIndex(IFWL_Widget* pWidget,
                          IFWL_ListItem* pItem,