* **Electron Version:**
  4.0.2
* **Operating System:**
  macOS 10.14.3
* **Last Known Working Electron version:**:
  1.7

### Expected Behavior
When creating a BrowserWindow it should not appear in the dock menu by defaults.

### Actual Behavior
It appears in the dock menu (example: `raven` in https://electronjs.org/docs/tutorial/macos-dock)

### To Reproduce
Just create new BrowserWindow, then right click on the app icon in the dock. (see https://electronjs.org/docs/tutorial/macos-dock)

At least it should be a way to control that, this can be achieve for top level window with:
`[window_ setExcludedFromWindowsMenu:YES];`, indeed [window isExcludedFromWindowsMenu] returns false by default, see

https://developer.apple.com/documentation/appkit/nsapplication/1428625-removewindowsitem
`Use the isExcludedFromWindowsMenu method of NSWindow if you want the item to remain excluded from the Window menu.`
https://developer.apple.com/documentation/appkit/nswindow/1419175-isexcludedfromwindowsmenu

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 void CreateForWebContents(content::WebContents*,
                                   base::WeakPtr<NativeWindow>);
  ~NativeWindowRelay() override;
  NativeWindow* GetNativeWindow() const { return native_window_.get(); }
  WEB_CONTENTS_USER_DATA_KEY_DECL();
 private:
  friend class content::WebContentsUserData<NativeWindow>;
  explicit NativeWindowRelay(base::WeakPtr<NativeWindow> window);
  base::WeakPtr<NativeWindow> native_window_;
};
}  
#endif