Fix Buffering Failure with src=
Fix Buffering Failure with src=

Because of the lack of tests (tests are coming) we did not see that the
buffering system was failing to find media source to check if it had
buffered to the end of the presentation.

This change adds the logic needed to know if it has buffered to the end
for each type of loaded content.

Issue #816
Issue #997

Change-Id: Ief9d4bdc94f3121f889a0efa24a8b3d78377bb9f

tvoli/shaka-player,shaka-project/shaka-player,tvoli/shaka-player,shaka-project/shaka-player,tvoli/shaka-player,shaka-project/shaka-player,tvoli/shaka-player,shaka-project/shaka-player