// Convert to binary object.
  var base64prefix = 'data:image/png;base64,';
  var binaryIndex = data.active.indexOf(base64prefix) + base64prefix.length;
  var imageData = data.active.substring(binaryIndex);
  var activeLength = imageData.length;
  var byteArray = new Uint8Array(activeLength);
  for (var i = 0; i < activeLength; i++) {
      byteArray[i] = imageData.charCodeAt(i) & 0xff;
  }

  var bb = new this.BlobBuilder();
  bb.append(byteArray.buffer);