HRESULT XPackageEstimateDownloadSize(  
         const char* packageIdentifier,  
         uint32_t selectorCount,  
         XPackageChunkSelector* selectors,  
         uint64_t* downloadSize,  
         bool* shouldPresentUserConfirmation  
)  

HRESULT ListDownloadSize(char* trackName)
{
    XPackageChunkSelector selector;
    selector.type = XPackageChunkSelectorType::Tag;
    selector.tag = trackName;

    char id[XPACKAGE_IDENTIFIER_MAX_LENGTH];
    HRESULT hr = XPackageGetCurrentProcessPackageIdentifier(_countof(id), id);
    if (FAILED(hr)) return hr;

    XPackageChunkAvailability availability;
    hr = XPackageFindChunkAvailability(id, 1, &selector, &availability);
    if (FAILED(hr)) return hr;

    if (availability == XPackageChunkAvailability::Installable)
    {
        uint64_t downloadSize;
        hr = XPackageEstimateDownloadSize(id, 1, &selector, &downloadSize, nullptr);
        if (FAILED(hr)) return hr;

        printf("Download Size for track %s: %I64u\n", trackName, downloadSize);
    }

    return hr;
}