### 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_win.cc
switch (w_param) {
    case SIZE_MAXIMIZED: {
      
      
      
      if (!has_frame()) {
        float scale_factor = display::win::ScreenWin::GetScaleFactorForHWND(
            GetAcceleratedWidget());
        int border =
            GetSystemMetrics(SM_CXFRAME) + GetSystemMetrics(SM_CXPADDEDBORDER);
        if (!thick_frame_) {
          border -= GetSystemMetrics(SM_CXBORDER);
        }
        root_view_->SetInsets(gfx::Insets(border).Scale(1.0f / scale_factor));
      }
      last_window_state_ = ui::SHOW_STATE_MAXIMIZED;
      if (consecutive_moves_) {
        last_normal_bounds_ = last_normal_bounds_before_move_;
      }
      NotifyWindowMaximize();
      break;
    }
    case SIZE_MINIMIZED:
      last_window_state_ = ui::SHOW_STATE_MINIMIZED;
      WINDOWPLACEMENT wp;
      wp.length = sizeof(WINDOWPLACEMENT);