尝试使用javascript将文件缩略图设置为Google Drive

我试图添加一个缩略图到我的文件，我使用Javascript上传到驱动器。我正试着按照https://developers.google.com/drive/v3/web/file#uploading_thumbnails

的指示去做。为了创建网络安全的base64图像，我使用在线转换器将一个简单的红色正方形图像转换为base64，生成了

data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVR42mP4z8DwHwAFAAH/VscvDQAAAABJRU5ErkJggg==

然后我把data:image/png;之后的所有东西都用_代替/，并删除=:

iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVR42mP4z8DwHwAFAAH_VscvDQAAAABJRU5ErkJggg

然后我在我的请求中添加了以下内容:

contentHints: {
    thumbnail: {
      image: "iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVR42mP4z8DwHwAFAAH_VscvDQAAAABJRU5ErkJggg",
      mimeType: "image/png"
    }
  }

然而，我没有看到任何缩略图为我的文件，无论是在谷歌驱动器的列表或网格视图。

有什么想法吗?

这是我的整个文件保存代码:

function saveFile(content) {
  var boundary = '-------314159265358979323846';
  var header = JSON.stringify({
    title: "My file",
    mimeType: "application/myFile",
    parents: ['root'],
    contentHints: {
      thumbnail: {
        image: "iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVR42mP4z8DwHwAFAAH_VscvDQAAAABJRU5ErkJggg",
        mimeType: "image/png"
      }
    }
  });
  var method = 'POST';
  var path = "/upload/drive/v2/files";
  var body = [
    "'r'n--" + boundary + "'r'nContent-Type: application/json'r'n'r'n" + header,
    "'r'n--" + boundary + "'r'nContent-Type: " + this.mimeType + "'r'n'r'n" + (content.getContentAsJSON()),
    "'r'n--" + boundary + "--"].join('');
  var request = gapi.client.request({
    path: path,
    method: method,
    params: {
      uploadType: 'multipart'
    },
    headers: {
      'Content-Type': 'multipart/related; boundary="' + boundary + '"'
    },
    body: body
  });
  request.execute(file);
};

var path = "/upload/drive/v3/files";