Split fwl/core class pt I.

xfa/fwl/core/cfwl_pushbutton.h

Index: xfa/fwl/core/cfwl_pushbutton.h
diff --git a/xfa/fwl/core/cfwl_pushbutton.h b/xfa/fwl/core/cfwl_pushbutton.h
index ad17406d12d59e33566c63485e086ca085e90e94..b35ed654744a1577fa2f4eafb361b01de944b406 100644
--- a/xfa/fwl/core/cfwl_pushbutton.h
+++ b/xfa/fwl/core/cfwl_pushbutton.h
@@ -9,15 +9,16 @@
 
 #include "xfa/fwl/core/cfwl_widget.h"
 #include "xfa/fwl/core/ifwl_pushbutton.h"
+#include "xfa/fwl/core/ifwl_widget.h"
 
-class CFWL_PushButton : public CFWL_Widget, public IFWL_PushButtonDP {
+class CFWL_PushButton : public CFWL_Widget, public IFWL_Widget::DataProvider {
  public:
   explicit CFWL_PushButton(const IFWL_App*);
   ~CFWL_PushButton() override;
 
   void Initialize();
 
-  // IFWL_DataProvider
+  // IFWL_Widget::DataProvider
   void GetCaption(IFWL_Widget* pWidget, CFX_WideString& wsCaption) override;
 };