1. Clarify intention of getAdGroupIndexForPositionUs and
getAdGroupIndexAfterPositionUs. Both methods are used for very
specific but different purposes and encode the logic of which
ads should be played at which time, so it's helpful to clarify
this in the documentation as well.
2. Change one usage getAdGroupIndexForPositionUs to use the already
existing nextAdGroupIndex. This is also more in line with the
intended usage as clarified in step 1.
3. Update MediaPeriodQueueTest for updateQueuedPeriods to only
look for duration changes in future periods, not in the
current one, because that's not handled MediaPeriodQueue for ads
and the test is just passing by chance now. Also remove wrong
advancePlaying() calls that are already implicitly included in
the preceding enqueueNext() call.
4. Fix a minor bug where post-roll ads are not checked whether they
are played already before using them as the next ad group. Also
added a test covering this case.
#minor-release
PiperOrigin-RevId: 370664131
26a6aad3e4