Merge "Minor changes to AudioTrack handling"

        removeMessages(token);

        if (token.getType() == MessageParams.TYPE_SYNTHESIS) {

            AudioTrack current = ((SynthesisMessageParams) token).getAudioTrack();

            if (current != null) {

                // Stop the current audio track if it's still playing.

                // The audio track is thread safe in this regard.

                current.stop();

            }

            mQueue.add(new ListEntry(SYNTHESIS_DONE, token, HIGH_PRIORITY));

        } else  {

            final MessageParams current = getCurrentParams();

        try {

            if (audioTrack != null) {

                audioTrack.flush();

                audioTrack.stop();

                if (DBG) Log.d(TAG, "Releasing audio track [" + audioTrack.hashCode() + "]");

                // The last call to AudioTrack.write( ) will return only after

                // all data from the audioTrack has been sent to the mixer, so

                // it's safe to release at this point.

                audioTrack.release();

            }

        } finally {