### 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
#include "ui/display/win/screen_win.h"
#include "ui/views/widget/desktop_aura/desktop_native_widget_aura.h"
#endif
namespace atom {
namespace {
#if defined(OS_WIN)
void FlipWindowStyle(HWND handle, bool on, DWORD flag) {
  DWORD style = ::GetWindowLong(handle, GWL_STYLE);
  if (on)
    style |= flag;
  else
    style &= ~flag;
  ::SetWindowLong(handle, GWL_STYLE, style);
}
gfx::Rect ScreenToDIPRect(HWND hwnd, const gfx::Rect& pixel_bounds) {
  float scale_factor = display::win::ScreenWin::GetScaleFactorForHWND(hwnd);
  gfx::Rect dip_rect = ScaleToRoundedRect(pixel_bounds, 1.0f / scale_factor);
  dip_rect.set_origin(
      display::win::ScreenWin::ScreenToDIPRect(hwnd, pixel_bounds).origin());
  return dip_rect;
}
gfx::Rect DIPToScreenRect(HWND hwnd, const gfx::Rect& pixel_bounds) {
  float scale_factor = display::win::ScreenWin::GetScaleFactorForHWND(hwnd);
  gfx::Rect screen_rect = ScaleToRoundedRect(pixel_bounds, scale_factor);
  screen_rect.set_origin(
      display::win::ScreenWin::DIPToScreenRect(hwnd, pixel_bounds).origin());
  return screen_rect;
}
#endif
class NativeWindowClientView : public views::ClientView {