AudioEffect acquires session
Currently, users of audio sessions, AudioTrack and AudioRecord,
are acquiring and releasing audio sessions according to their
life-cycle. AudioEffect instances were not counting as users
of an audio session. This caused an effect used on a session
to be purged by AudioFlinger::purgeStaleEffects_l() whenever
the last user of that session went away.
This CL makes AudioEffect acquire and release a session when
created and destroyed.
Bug
15432115
Change-Id: I922532150009988d43872f9b5928044a830ae0b3