### 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
if (content_view()) {
    root_view_->RemoveChildView(content_view());
  }
  set_content_view(view);
  focused_view_ = view;
  root_view_->AddChildView(content_view());
  root_view_->Layout();
}
void NativeWindowViews::Close() {
  if (!IsClosable()) {
    WindowList::WindowCloseCancelled(this);
    return;
  }
  widget()->Close();
}
void NativeWindowViews::CloseImmediately() {
  widget()->CloseNow();
}
void NativeWindowViews::Focus(bool focus) {
  
  if (!IsVisible())
    return;
  if (focus) {
    widget()->Activate();
  } else {
    widget()->Deactivate();
  }
}
bool NativeWindowViews::IsFocused() {