### 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 defined(OS_WIN)
  DWORD affinity = enable ? WDA_MONITOR : WDA_NONE;
  ::SetWindowDisplayAffinity(GetAcceleratedWidget(), affinity);
#endif
}
void NativeWindowViews::SetFocusable(bool focusable) {
#if defined(OS_WIN)
  LONG ex_style = ::GetWindowLong(GetAcceleratedWidget(), GWL_EXSTYLE);
  if (focusable)
    ex_style &= ~WS_EX_NOACTIVATE;
  else
    ex_style |= WS_EX_NOACTIVATE;
  ::SetWindowLong(GetAcceleratedWidget(), GWL_EXSTYLE, ex_style);
  SetSkipTaskbar(!focusable);
  Focus(false);
#endif
}
void NativeWindowViews::SetMenu(AtomMenuModel* menu_model) {
#if defined(USE_X11)
  if (menu_model == nullptr) {
    global_menu_bar_.reset();
    root_view_->UnregisterAcceleratorsWithFocusManager();
    return;
  }
  if (!global_menu_bar_ && ShouldUseGlobalMenuBar())
    global_menu_bar_.reset(new GlobalMenuBarX11(this));
  
  if (global_menu_bar_ && global_menu_bar_->IsServerStarted()) {
    root_view_->RegisterAcceleratorsWithFocusManager(menu_model);