### 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
NotifyWindowMove();
}
void NativeWindowViews::HandleKeyboardEvent(
    content::WebContents*,
    const content::NativeWebKeyboardEvent& event) {
#if defined(OS_LINUX)
  if (event.windows_key_code == ui::VKEY_BROWSER_BACK)
    NotifyWindowExecuteAppCommand(kBrowserBackward);
  else if (event.windows_key_code == ui::VKEY_BROWSER_FORWARD)
    NotifyWindowExecuteAppCommand(kBrowserForward);
#endif
  keyboard_event_handler_->HandleKeyboardEvent(event,
                                               root_view_->GetFocusManager());
  root_view_->HandleKeyEvent(event);
}
#if defined(OS_LINUX)
void NativeWindowViews::OnMouseEvent(ui::MouseEvent* event) {