Merge "adb: fix deadlock between transport_unref and usb_close." into oc-dr1-dev

static void transport_unref(atransport* t) {

    CHECK(t != nullptr);

    std::lock_guard<std::mutex> lock(transport_lock);

    CHECK_GT(t->ref_count, 0u);

    t->ref_count--;

    if (t->ref_count == 0) {

    size_t old_refcount = t->ref_count--;

    CHECK_GT(old_refcount, 0u);

    if (old_refcount == 1u) {

        D("transport: %s unref (kicking and closing)", t->serial);

        t->close(t);

        remove_transport(t);

    } else {

        D("transport: %s unref (count=%zu)", t->serial, t->ref_count);

        D("transport: %s unref (count=%zu)", t->serial, old_refcount - 1);

    }

}

    // class in one go is a very large change. Given how bad our testing is,

    // it's better to do this piece by piece.

    atransport(ConnectionState state = kCsOffline) : connection_state_(state) {

    atransport(ConnectionState state = kCsOffline) : ref_count(0), connection_state_(state) {

        transport_fde = {};

        protocol_version = A_VERSION;

        max_payload = MAX_PAYLOAD;

    int fd = -1;

    int transport_socket = -1;

    fdevent transport_fde;

    size_t ref_count = 0;

    std::atomic<size_t> ref_count;

    uint32_t sync_token = 0;

    bool online = false;

    TransportType type = kTransportAny;