Keep extra reference of shared memory for AudioTrack data callback.

Keep extra reference of shared memory for AudioTrack data callback so
that the shared memory will remain valid when the native track is
restored.

Issue: FP3-A13#246
Bug: 274815060
Test: manual
Test: atest AudioTrackTest
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:d42567cfabc94bf2ba0e2fe35c5183883bc563c8)

Merged-In: I76ce5b7b14732eb6921791c7ab8f283b447710eb
Change-Id: I76ce5b7b14732eb6921791c7ab8f283b447710eb
2 files changed