anchor.diff:  import 'lib/launch.dart';
   import 'lib/mobile/android_rsa.dart';
   import 'lib/mobile/deploy.dart';
  +import 'lib/mobile/usb.dart';
   import 'lib/navigation.dart';
   import 'lib/package_mgmt/pub.dart';
   import 'lib/package_mgmt/bower.dart';
  
positive.code:     });
    }
  
    void _enableInputs([_]) {
      _pushUrlElement.disabled = !_ipElement.checked;
      _usbDevices.disabled = _ipElement.checked;
      _addDeviceButton.disabled = _ipElement.checked;
    }
  
     /**
     * 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() {
      Completer completer = new Completer();
  
      Function cb = (result) {
        completer.complete();
        _loadUsbDevices();
      };
  
      var context = js.context['chrome']['usb'];
      var options = new js.JsObject.jsify({'filters': [new js.JsObject.jsify({
        'interfaceClass': 0xff,
        'interfaceSubclass': 0x42,
        'interfaceProtocol': 0x01
      })]});
      try {
        context.callMethod("getUserSelectedDevices", [options, cb]);
      } catch (e) {
        // user cancelled the operation.
      }
      return completer.future;
    }
  
    void _toggleProgressVisible(bool visible) {
  
negative.code:     }
    }
  
    Future<List> _loadDevices() => UsbUtil.getDevices();
  
    void _loadUsbDevices() {
      _usbDevices.length = 0;
  