Protect sp assignments in RemoteDataSource.

sp assignments is not thread safe and close also can be called from
binder clean-up procedure on the separate thread.

Test: cts-tradefed run cts -m CtsMediaTestCases -t android.media.cts.MediaPlayerTest#testVorbisCrash
Bug: 62251555
Change-Id: I3e5f42d87b490f4aadfa17276632783545611cdc
1 file changed