andrewlewis bf65df1b35 Allow ClippingMediaPeriod to be used on its own.
ClippingMediaPeriod may be a useful component for other MediaSources too so
remove its dependency on ClippingMediaSource.

Also allow the clipping end point to be TIME_END_OF_SOURCE, in which case
the clipping window extends to the end of the wrapped period.

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MOE_MIGRATED_REVID=144056285
2017-01-10 10:51:49 +00:00
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2016-11-25 20:18:32 +00:00