GoogleWebAuthorizationBroker.AuthorizeAsync Hang when user closes browser about google-api-dotnet-client HOT 5 OPEN

Also happens in my C# VSTO, which can cause Excel to hang and force termination 
at the process.

I got the same issue.
Tried to fix this like that : 

using (var cts = new CancellationTokenSource())
{
    cts.CancelAfter(TimeSpan.FromMinutes(1));

    return GoogleWebAuthorizationBroker.AuthorizeAsync(
                            clientSecrets,
                            new[] { GOOGLE_SITES_SCOPE },
                            "user",
                            cts.Token,
                            _fileDataStore).Result;
}

but cancellation does not always occur.

I tried the same thing but with a longer TimeSpan.  I haven't been able to 
figure out why the timeout won't work in some cases.  I have a higher successes 
rate in my console apps than VSTO, so I think it might have something to do 
with the starting environment.