Removes aura::Window::set_user_data()

ui/aura/window.h

Index: ui/aura/window.h
diff --git a/ui/aura/window.h b/ui/aura/window.h
index ba5b07a78b74112487d00162e3f39f343db59b9e..80770c17b4d567b0980b2b9652e028ca05095cff 100644
--- a/ui/aura/window.h
+++ b/ui/aura/window.h
@@ -135,10 +135,6 @@ class AURA_EXPORT Window : public ui::LayerDelegate,
   void set_host(WindowTreeHost* host) { host_ = host; }
   bool IsRootWindow() const { return !!host_; }
 
-  // The Window does not own this object.
-  void set_user_data(void* user_data) { user_data_ = user_data; }
-  void* user_data() const { return user_data_; }
-
   // Changes the visibility of the window.
   void Show();
   void Hide();
@@ -507,8 +503,6 @@ class AURA_EXPORT Window : public ui::LayerDelegate,
   std::unique_ptr<LayoutManager> layout_manager_;
   std::unique_ptr<ui::EventTargeter> targeter_;
 
-  void* user_data_;
-
   // Makes the window pass all events through to any windows behind it.
   bool ignore_events_;