<!--  As an open source project with a dedicated but small maintainer team, it can sometimes take a long time for issues to be addressed so please be patient and we will get back to you as soon as we can.
-->

### Preflight Checklist
<!-- Please ensure you've completed the following steps by replacing [ ] with [x]-->

* [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.15
* **Operating System:**
  * Windows 10 (1903)
* **Last Known Working Electron version:**
  * 5.0.8

### Expected Behaviour
When a frameless window is maximized, and then enters full screen from that state, it should fill the entire screen with no border.

### Actual Behaviour
If a frameless window enters fullscreen from a maximized state, a ~10px white border appears all around the screen.
(Hard to show in a screenshot on a white page…)

### To Reproduce
Fiddle gist: https://gist.github.com/caesar/12c97746e9d8b0e9bd2ee7e4958c63ad

### Screenshots
It's hard to see the issue here because the border is white and so is the background of this page… but if you look carefully, the second time I the window enters fullscreen (when it does it from maximized), a white border appears.
![Kapture 2019-07-26 at 23 28 21](https://user-images.githubusercontent.com/1566516/61984625-20991200-affd-11e9-9e8a-9b4faed1fea8.gif)

shell/browser/native_window_views_win.cc
last_normal_bounds_ = last_normal_bounds_candidate_;
        last_normal_bounds_candidate_ = GetBounds();
        consecutive_moves_ = true;
      }
      return false;
    }
    case WM_ENDSESSION: {
      if (w_param) {
        NotifyWindowEndSession();
      }
      return false;
    }
    case WM_PARENTNOTIFY: {
      if (LOWORD(w_param) == WM_CREATE) {
        
        
        
        
        
        if (!legacy_window_) {
          legacy_window_ = reinterpret_cast<HWND>(l_param);
        }
      }
      return false;
    }
    default:
      return false;
  }
}
void NativeWindowViews::HandleSizeEvent(WPARAM w_param, LPARAM l_param) {