Merge "midi: Use std::optional instead of std::unique_ptr"

status_t MidiDeviceInfo::readStringVector(

        const Parcel* parcel, Vector<String16> *vectorPtr, size_t defaultLength) {

    std::unique_ptr<std::vector<std::unique_ptr<String16>>> v;

    std::optional<std::vector<std::optional<String16>>> v;

    status_t result = parcel->readString16Vector(&v);

    if (result != OK) return result;

    vectorPtr->clear();

    if (v.get() != nullptr) {

    if (v) {

        for (const auto& iter : *v) {

            if (iter.get() != nullptr) {

            if (iter) {

                vectorPtr->push_back(*iter);

            } else {

                vectorPtr->push_back(String16());