Also added Period::GetAdaptationSets and
AdaptationSet::GetRepresentations.
Instead of implementing GetDurationSeconds in all MpdBuilder classes
(MpdBuilder/Period/Adaptation/Representation) like what we used to do
with GetEarliestTimestamp, the two new functions allows MpdBuilder to
iterate through the Representations to get durations.
Also updates GetEarliestTimestamp functions to use the same iteration
method.
Change-Id: I682b70c07c248c0f6511ec3d9019086f986ee10e
Move AdaptationSet related functions to the new Period class, which
maps to <Period> element and provides methods to add AdaptationSets.
Change-Id: I0fee290769fbe9a6355cc1b8c86baec8fbc4b4fd
Move AdaptationSet related tests to adaptation_set_unittest.cc and
Representation related tests to representation_unittest.cc.
Change-Id: I360e9aea3ba08a32e5ba3b0e8b34345f2b3f0b20
KongQun Yang