### 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
public:
  NativeWindowClientView(views::Widget* widget,
                         views::View* root_view,
                         NativeWindowViews* window)
      : views::ClientView(widget, root_view), window_(window) {}
  ~NativeWindowClientView() override = default;
  bool CanClose() override {
    window_->NotifyWindowCloseButtonClicked();
    return false;
  }
 private:
  NativeWindowViews* window_;
  DISALLOW_COPY_AND_ASSIGN(NativeWindowClientView);
};
}  
NativeWindowViews::NativeWindowViews(const mate::Dictionary& options,