tonihei 84f4fe5cf9 Recover from empty timelines.
(Related to GitHub #1706)

When the timeline becomes empty, the playback state transitions to "ended".
When the timeline becomes non-empty again, exceptions are thrown because MSG_DO_SOME_WORK is still regularly sent and media periods are getting prepared.

This change ensures that no MSG_DO_SOME_WORK messages are sent in "ended" state.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=160537147
2017-06-30 16:44:14 +01:00
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2017-06-30 16:44:14 +01:00