c# web api post with progress reporting

WebApiPostWithProgress.cs

//in setup define client and progress reporter
 var httpProgressHandler = new ProgressMessageHandler();
httpProgressHandler.InnerHandler = new HttpClientHandler();
var client = new HttpClient(httpProgressHandler) { BaseAddress = new Uri(Settings.Default.ServerUrl) };

//register to use elsewhere in the application, note it is better to resuse for lifetime of application than create for every call
Mvx.RegisterSingleton(client);
Mvx.RegisterSingleton(httpProgressHandler);


//Where we are going to use it
protected readonly ProgressMessageHandler httpProgressHandler = Mvx.Resolve<ProgressMessageHandler>();
private IProgress<UploadProgress> httpProgressReport;

public async Task<bool> PostAndReportProgress(Object someObject, CancellationToken cancellationToken, IProgress<UploadProgress> progress)
{
   var returnValue = false;
   httpProgressReport = progress;
   httpProgressHandler.HttpSendProgress += HttpProgressHandlerOnHttpSendProgress;
   //see other gist for creating a multipart upload object, omitted here
   var result = await httpClient.PostAsync("Upload/", someObject, cancellationToken);
   if (result.IsSuccessStatusCode)
   {
      returnValue = true;
   }
   httpProgressHandler.HttpSendProgress -= HttpProgressHandlerOnHttpSendProgress;
   return returnValue;
}

private void HttpProgressHandlerOnHttpSendProgress(object sender, HttpProgressEventArgs httpProgressEventArgs)
        {
            if (null != httpProgressReport)
            {
                var progress = new UploadProgress();
                progress.PercentComplete = httpProgressEventArgs.ProgressPercentage;
                progress.Status = string.Format("{0} MB uploaded of {1} MB", httpProgressEventArgs.BytesTransferred / 1048576, httpProgressEventArgs.TotalBytes / 1048576);                
                httpProgressReport.Report(progress);
            }
        }

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