* **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_views.h
static std::set<NativeWindowViews*> forwarding_windows_;
  static HHOOK mouse_hook_;
  bool forwarding_mouse_messages_ = false;
  HWND legacy_window_ = NULL;
  bool layered_ = false;
#endif
  
  std::unique_ptr<views::UnhandledKeyboardEventHandler> keyboard_event_handler_;
  
  
  std::unique_ptr<SkRegion> draggable_region_;  
  
  bool is_enabled_ = true;
  
  
  unsigned int num_modal_children_ = 0;
  bool use_content_size_ = false;
  bool movable_ = true;
  bool resizable_ = true;
  bool maximizable_ = true;
  bool minimizable_ = true;
  bool fullscreenable_ = true;
  std::string title_;
  gfx::Size widget_size_;
  double opacity_ = 1.0;
  DISALLOW_COPY_AND_ASSIGN(NativeWindowViews);
};
}  
#endif