Fix a crash for a race condition during Bluetooth shutdown

This race condition is triggered when A2DP audio is streaming on shutdown:
"btif_a2dp_on_stopped() -> btif_media_task_aa_tx_flush_req()" is called
to stop the particular audio stream, and this happens right after
the "cleanup() -> btif_a2dp_stop_media_task()" processing during
the shutdown of the Bluetooth stack.

Bug: 22602117
Change-Id: I5de6a8f15b6a2771dde2e299a5b60554063696a2
1 file changed
tree: e0290a4f4bdea236fa4522c0a297a65e60ffb1d3
  1. gki/
  2. system/
  3. Android.mk
  4. CleanSpec.mk
  5. MODULE_LICENSE_APACHE2
  6. NOTICE