Remove include only fwl.h and IWYU.

xfa/include/fwl/basewidget/fwl_pushbutton.h

Index: xfa/include/fwl/basewidget/fwl_pushbutton.h
diff --git a/xfa/include/fwl/basewidget/fwl_pushbutton.h b/xfa/include/fwl/basewidget/fwl_pushbutton.h
index 500cc0dcc14fa3660f8c70227cd3cd53d6e3be30..3e5acd11b0e669c329e74d07dd8e2f5798887442 100644
--- a/xfa/include/fwl/basewidget/fwl_pushbutton.h
+++ b/xfa/include/fwl/basewidget/fwl_pushbutton.h
@@ -7,10 +7,9 @@
 #ifndef XFA_INCLUDE_FWL_BASEWIDGET_FWL_PUSHBUTTON_H_
 #define XFA_INCLUDE_FWL_BASEWIDGET_FWL_PUSHBUTTON_H_
 
-class CFWL_WidgetImpProperties;
-class IFWL_Widget;
-class IFWL_PushButtonDP;
-class IFWL_PushButton;
+#include "xfa/include/fwl/core/fwl_theme.h"
+#include "xfa/src/fwl/src/core/include/fwl_widgetimp.h"
+
 #define FWL_CLASS_PushButton L"FWL_PUSHBUTTON"
 #define FWL_CLASSHASH_PushButton 3521614244
 #define FWL_STYLEEXT_PSB_Left (0L << 0)
@@ -40,6 +39,7 @@ class IFWL_PushButton;
 #define FWL_PARTSTATE_PSB_Disabled (4L << 0)
 #define FWL_PARTSTATE_PSB_Focused (1L << 3)
 #define FWL_PARTSTATE_PSB_Mask (7L << 0)
+
 class IFWL_PushButtonDP : public IFWL_DataProvider {
  public:
   virtual CFX_DIBitmap* GetPicture(IFWL_Widget* pWidget) = 0;