
MPD file may include multiple EventStreams in its Periods, which contains Events that the application may need to handle/respond to. This change adds support for parsing the EventStream/Event nodes from MPD file, and exposing these EventStreams as a metadata sample stream that application can respond in a similar way to other metadata events. ------------- Created by MOE: https://github.com/google/moe MOE_MIGRATED_REVID=175017697