MediaKeySession class

1. Properties
2. closed
3. expiration
4. keyStatuses
5. onMessage
6. sessionId
7. hashCode
8. on
9. runtimeType
10. Methods
11. close
12. generateRequest
13. load
14. remove
15. addEventListener
16. dispatchEvent
17. noSuchMethod
18. removeEventListener
19. toString
20. Operators
21. operator ==
22. Constants
23. messageEvent