Merge "Make prepare properly report failure again" into lmp-dev

    int32_t totalBitrate = 0;

    for (size_t i = 0; i < extractor->countTracks(); ++i) {

    size_t numtracks = extractor->countTracks();

    if (numtracks == 0) {

        return UNKNOWN_ERROR;

    }

    for (size_t i = 0; i < numtracks; ++i) {

        sp<MediaSource> track = extractor->getTrack(i);

        sp<MetaData> meta = extractor->getTrackMetaData(i);