anchor.diff:  
     static const Duration animationDelay = Duration(milliseconds: 500);
     static const Duration defaultHideDelay = Duration(seconds: 4);
  -  static const Duration extendedHideDelay = Duration(seconds: 8);
  +  static const Duration extendedHideDelay = Duration(seconds: 10);
   
     final String title;
     @required
  
positive.code: 
      final droppedFile = files.first;
      if (droppedFile.type != 'application/json') {
        toast('${droppedFile.type} is not a supported file type.\n Please import '
            'a .json file that was exported from Dart DevTools.');
        return;
      }
  
      final FileReader reader = FileReader();
      reader.onLoad.listen((_) {
        final Map<String, dynamic> import = jsonDecode(reader.result);
        final devToolsScreen = import['dartDevToolsScreen'];
  
        if (devToolsScreen == null) {
          toast(
            'The imported file is not a Dart DevTools file. At this time, '
            'DevTools only supports importing files that were originally exported'
            ' from DevTools.',
            hideDelay: Toast.extendedHideDelay,
          );
          return;
        }
  
        // TODO(jacobr): add the inspector handling case here once the inspector
        // can be exported.
        switch (devToolsScreen) {
          case timelineScreenId:
            TimelineScreen timelineScreen = screens.firstWhere(
              (screen) => screen.id == timelineScreenId,
              orElse: () => null,
            );
            if (timelineScreen == null) {
              addScreen(timelineScreen = TimelineScreen(disabled: false));
            }
            connectDialog.hide();
            importMessage.hide();
            importMode = true;
            navigateTo(timelineScreenId);
            timelineScreen.loadFromImport(import);
            break;
          default:
            toast(
              'Could not import file. The imported file is from an unrecognized '
              'DevTools screen: $devToolsScreen.',
              hideDelay: Toast.extendedHideDelay,
            );
        }
      });
  
  
negative.code:     } catch (e) {
        toast('Could not import file: $e');
      }
    }
  
    void _importTimeline(Map<String, dynamic> import) {
      TimelineScreen timelineScreen = screens.firstWhere(
        (screen) => screen.id == timelineScreenId,
        orElse: () => null,
      );
      if (timelineScreen == null) {
        addScreen(timelineScreen = TimelineScreen(disabled: false));
      }
      _enterImportMode();
      navigateTo(timelineScreenId);
      timelineScreen.loadFromImport(import);
    }
  
    void _enterImportMode() {
      connectDialog.hide();
      importMessage.hide();
      importMode = true;
    }
  
    void exitImportMode() {
  