Merge "Check the isInUse with the lock held in MessageQueue" into rvc-dev am:...

        if (msg.target == null) {

            throw new IllegalArgumentException("Message must have a target.");

        }

        synchronized (this) {

            if (msg.isInUse()) {

                throw new IllegalStateException(msg + " This message is already in use.");

            }

        synchronized (this) {

            if (mQuitting) {

                IllegalStateException e = new IllegalStateException(

                        msg.target + " sending message to a Handler on a dead thread");