Need a Linux impl for https://github.com/electron/electron/pull/12485
atom/browser/native_window.h
double aspect_ratio_ = 0.0;
  gfx::Size aspect_ratio_extraSize_;
  
  NativeWindow* parent_ = nullptr;
  
  bool is_modal_ = false;
  
  std::list<NativeBrowserView*> browser_views_;
  
  base::ObserverList<NativeWindowObserver> observers_;
  base::WeakPtrFactory<NativeWindow> weak_factory_;
  DISALLOW_COPY_AND_ASSIGN(NativeWindow);
};
class NativeWindowRelay
    : public content::WebContentsUserData<NativeWindowRelay> {
 public:
  static const void* const kNativeWindowRelayUserDataKey;
  static void CreateForWebContents(content::WebContents*,
                                   base::WeakPtr<NativeWindow>);
  ~NativeWindowRelay() override;
  NativeWindow* GetNativeWindow() const { return native_window_.get(); }
 private:
  friend class content::WebContentsUserData<NativeWindow>;
  explicit NativeWindowRelay(base::WeakPtr<NativeWindow> window);
  base::WeakPtr<NativeWindow> native_window_;
};
}  
#endif