MediaKeySession：sessionId 属性
Baseline
Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since 2019年3月.
MediaKeySession 接口的 sessionId 只读属性包含由内容解密模块（CDM）为当前媒体对象及其关联的密钥或许可证生成的唯一字符串。