[RESTRICT AUTOMERGE] Fix double free of play policy in a race condition.

The mPlayPolicy can be freed twice if there is a race condition.
mPlayPolicy should be protected with a mutex lock.

SafetyNet logging is not added to avoid log spamming. The
mutex lock is called whenever a license request is made.
That can happen quite often.

Bug: 176168330

Test: TreeHugger build
Change-Id: Idccbc768c17676087dd66fcdd568bac402202e8f
(cherry picked from commit a9249b23)