### Preflight Checklist

- [X] I have read the [Contributing Guidelines](https://github.com/electron/electron/blob/main/CONTRIBUTING.md) for this project.
- [X] I agree to follow the [Code of Conduct](https://github.com/electron/electron/blob/main/CODE_OF_CONDUCT.md) that this project adheres to.
- [X] I have searched the [issue tracker](https://www.github.com/electron/electron/issues) for a bug report that matches the one I want to file, without success.

### Electron Version

16.0.0

### What operating system are you using?

Windows

### Operating System Version

WIN10 20H2

### What arch are you using?

x64

### Last Known Working Electron version

_No response_

### Expected Behavior

 win.webContents.savePage('d:/aaaaaa.html', 'HTMLComplete').then(() => {
      console.log('Page was saved successfully.')
    }).catch(err => {
      console.log(err)
    })

it will generate a html page file at d: 

### Actual Behavior

savePage has three formats that can be used

if use HTMLComplete
 only produced a aaaaaa_files empty folder

if use HTMLonly 
No files are generated nor error callbacks are generated

MHTML option works fine

### Testcase Gist URL

_No response_

### Additional Information

_No response_
shell/browser/api/electron_api_web_contents.cc
base::ScopedBlockingCall scoped_blocking_call(FROM_HERE,
                                                base::BlockingType::WILL_BLOCK);
  DCHECK(!path.empty());
  base::AppendToFile(path, content);
}
PrefService* GetPrefService(content::WebContents* ontents) {
  auto* context = ontents->GetBrowserContext();
  return static_cast<electron::ElectronBrowserContext*>(context)->prefs();
}
std::map<std::string, std::string> GetAddedFileSystemPaths(
    content::WebContents* ontents) {
  auto* pref_service = GetPrefService(ontents);
  const base::DictionaryValue* file_system_paths_value =
      pref_service->GetDictionary(prefs::kDevToolsFileSystemPaths);
  std::map<std::string, std::string> result;
  if (file_system_paths_value) {
    base::DictionaryValue::Iterator it(*file_system_paths_value);
    for (; !it.IsAtEnd(); it.Advance()) {
      std::string type =
          it.value().is_string() ? it.value().GetString() : std::string();
      result[it.key()] = type;
    }
  }
  return result;
}
bool IsDevToolsFileSystemAdded(content::WebContents* ontents,