anchor.diff:        for (int i = 0; i < 10; i++) {
           await device.shellExec('input', <String>['keyevent', 'KEYCODE_BACK']);
           await new Future<Null>.delayed(const Duration(milliseconds: 1000));
  -        final String output = await device.shellEval('am', <String>['start', '-n', 'io.flutter.examples.gallery/io.flutter.app.FlutterActivity']);
  +        final String output = await device.shellEval('am', <String>['start', '-n', '$packageName/$activityName']);
           print(output);
           if (output.contains('Error'))
             return new TaskResult.failure('unable to launch activity');
  
positive.code:   return new AndroidBackButtonMemoryTest(
      '${flutterDirectory.path}/examples/flutter_gallery',
      'io.flutter.examples.gallery',
    );
  }
  
  
negative.code: class AndroidBackButtonMemoryTest {
    final String testDirectory;
    final String packageName;
    final String activityName;
  
    AndroidBackButtonMemoryTest(this.testDirectory, this.packageName, this.activityName);
  
    Future<TaskResult> call() {
      return inDirectory(testDirectory, () async {
  