### 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

It would appear that `app.focus()` stopped working in Electron 6, and remains broken in Electron 8.

* **Electron Version:**
  * 8.0.3
* **Operating System:**
  * macOS
* **Last Known Working Electron version:**
  * 5.0.13

### Expected Behavior
`app.focus()` should bring the application to the foreground.

### Actual Behavior
`app.focus()` does nothing.

### To Reproduce

Fiddle: https://gist.github.com/a772265b312329e3f3bc1feb7b6aff7d

1) Start this fiddle.
2) As soon as the window pops up, select another application so that Electron is in the background.
3) Within 5 seconds, the app will attempt to focus itself to no avail.

shell/browser/browser_win.cc
const LoginItemSettings& options) {
  LoginItemSettings settings;
  base::string16 keyPath = L"Software\\Microsoft\\Windows\\CurrentVersion\\Run";
  base::win::RegKey key(HKEY_CURRENT_USER, keyPath.c_str(), KEY_ALL_ACCESS);
  base::string16 keyVal;
  if (!FAILED(key.ReadValue(GetAppUserModelID(), &keyVal))) {
    base::string16 exe = options.path;
    if (FormatCommandLineString(&exe, options.args)) {
      settings.open_at_login = keyVal == exe;
    }
  }
  return settings;
}
PCWSTR Browser::GetAppUserModelID() {
  return GetRawAppUserModelID();
}
std::string Browser::GetExecutableFileVersion() const {
  base::FilePath path;
  if (base::PathService::Get(base::FILE_EXE, &path)) {
    base::ThreadRestrictions::ScopedAllowIO allow_io;
    std::unique_ptr<FileVersionInfo> version_info = FetchFileVersionInfo();
    return base::UTF16ToUTF8(version_info->product_version());
  }
  return ELECTRON_VERSION_STRING;
}
std::string Browser::GetExecutableFileProductName() const {