wayland: define base:NativeEvent for Wayland

ui/wayland/wayland_widget.h

Index: ui/wayland/wayland_widget.h
diff --git a/ui/wayland/wayland_widget.h b/ui/wayland/wayland_widget.h
index f274141d0f951f72f63dd598d8338c8a823af964..1c4e40dc888f0cdee710675ff2ebd601d5946487 100644
--- a/ui/wayland/wayland_widget.h
+++ b/ui/wayland/wayland_widget.h
@@ -5,7 +5,11 @@
 #ifndef UI_WAYLAND_WAYLAND_WIDGET_H_
 #define UI_WAYLAND_WAYLAND_WIDGET_H_
 
-#include "ui/wayland/events/wayland_event.h"
+namespace base {
+namespace wayland {
+union WaylandEvent;
+}
+}
 
 namespace ui {
 
@@ -14,13 +18,13 @@ class WaylandWidget {
  public:
   virtual ~WaylandWidget() {}
 
-  virtual void OnMotionNotify(WaylandEvent event) = 0;
-  virtual void OnButtonNotify(WaylandEvent event) = 0;
-  virtual void OnKeyNotify(WaylandEvent event) = 0;
-  virtual void OnPointerFocus(WaylandEvent event) = 0;
-  virtual void OnKeyboardFocus(WaylandEvent event) = 0;
+  virtual void OnMotionNotify(base::wayland::WaylandEvent event) = 0;
+  virtual void OnButtonNotify(base::wayland::WaylandEvent event) = 0;
+  virtual void OnKeyNotify(base::wayland::WaylandEvent event) = 0;
+  virtual void OnPointerFocus(base::wayland::WaylandEvent event) = 0;
+  virtual void OnKeyboardFocus(base::wayland::WaylandEvent event) = 0;
 
-  virtual void OnGeometryChange(WaylandEvent event) = 0;
+  virtual void OnGeometryChange(base::wayland::WaylandEvent event) = 0;
 };
 
 }  // namespace ui