### Preflight Checklist
* [x] I have read the [Contributing Guidelines](https://github.com/electron/electron/blob/master/CONTRIBUTING.md) for this project.
* [x] I agree to follow the [Code of Conduct](https://github.com/electron/electron/blob/master/CODE_OF_CONDUCT.md) that this project adheres to.
* [x] I have searched the issue tracker for an issue that matches the one I want to file, without success.

### Issue Details

* **Electron Version:**
  * 6.0.0-beta.3
* **Operating System:**
  * Windows 10 (1809)
* **Last Known Working Electron version:**:
  * 5.0.1

### Expected Behavior
Dragging your mouse to the bottom of the screen with a maximized frameless window and a hidden Windows taskbar should make the taskbar appear.

### Actual Behavior
The taskbar does not appear.

### To Reproduce

* Ensure you have Taskbar hiding enabled
![image](https://user-images.githubusercontent.com/144914/57793291-d12d9000-76f5-11e9-8c63-178e928a5358.png)

```sh
$ git clone https://github.com/adill/electron-quick-start -b no-taskbar-unhide
$ npm install
$ npm start || electron .
```

* Move your mouse to the bottom of the screen

### Screenshots

### Additional Information

atom/browser/native_window_views.cc
const gfx::Rect& bounds) {
  if (changed_widget != widget())
    return;
  
  
  const auto new_bounds = GetBounds();
  if (widget_size_ != new_bounds.size()) {
    int width_delta = new_bounds.width() - widget_size_.width();
    int height_delta = new_bounds.height() - widget_size_.height();
    for (NativeBrowserView* item : browser_views()) {
      NativeBrowserViewViews* native_view =
          static_cast<NativeBrowserViewViews*>(item);
      native_view->SetAutoResizeProportions(widget_size_);
      native_view->AutoResize(new_bounds, width_delta, height_delta);
    }
    NotifyWindowResize();
    widget_size_ = new_bounds.size();
  }
}
void NativeWindowViews::OnWidgetDestroying(views::Widget* widget) {