title: update progress bar with Firebase uploading
body: <p>I tried to add a progress bar to uploading files on firebase. but unfortunalty it does not indicate upload progress. both logcat &amp; progress bar  only indicate when file reached to 100%</p>
  
  <pre><code>   uploadTask.addOnProgressListener(new OnProgressListener&lt;UploadTask.TaskSnapshot&gt;() {
              @Override
              public void onProgress(UploadTask.TaskSnapshot taskSnapshot) {
                  double progress = 100.0 * (taskSnapshot.getBytesTransferred() / taskSnapshot.getTotalByteCount());
                  System.out.println("Upload is " + progress + "% done");
              int currentprogress = (int) progress;
                  progressBar.setProgress(currentprogress);
              }
          }).addOnPausedListener(new OnPausedListener&lt;UploadTask.TaskSnapshot&gt;() {
              @Override
              public void onPaused(UploadTask.TaskSnapshot taskSnapshot) {
                  System.out.println("Upload is paused");
              }
          });
  </code></pre>