anchor.diff:      }
     }
   
  -  Future<List> _loadDevices() {
  -    Completer completer = new Completer();
  -
  -    Function cb = (result) {
  -      completer.complete(result);
  -    };
  -
  -    var context = js.context['chrome']['usb'];
  -    var options = new js.JsObject.jsify({});
  -    try {
  -      context.callMethod("getDevices", [options, cb]);
  -    } catch (e) {
  -      // user cancelled the operation.
  -    }
  -    return completer.future;
  -  }
  +  Future<List> _loadDevices() => UsbUtil.getDevices();
   
     void _loadUsbDevices() {
       _usbDevices.length = 0;
  
positive.code: import 'lib/launch.dart';
  import 'lib/mobile/android_rsa.dart';
  import 'lib/mobile/deploy.dart';
  import 'lib/navigation.dart';
  import 'lib/package_mgmt/pub.dart';
  import 'lib/package_mgmt/bower.dart';
  
negative.code:     });
    }
  
     /**
     * Opens a dialog and provides a list of active adb devices to select from.
     * It allows to select a single device at a time.
    */
    Future _addDevice() {
      return UsbUtil.getUserSelectedDevices().then((devices) {
        _loadUsbDevices();
      });
    }
  
    void _enableInputs([_]) {
      _pushUrlElement.disabled = !_ipElement.checked;
      _usbDevices.disabled = _ipElement.checked;
      _addDeviceButton.disabled = _ipElement.checked;
    }
  
    void _toggleProgressVisible(bool visible) {
  