anchor.diff:            _normalizeVmServiceUri(serviceProtocolUri).toString();
       }
   
  -    String url = devToolsUrl.toString();
  -    // If serviceProtocolUri != null, add it to the url.
  -    if (serviceProtocolUri != null) {
  -      url = Uri.parse(devToolsUrl).replace(queryParameters: {
  -        'uri': serviceProtocolUri,
  -      }).toString();
  +    final queryParameters = {
  +      if (serviceProtocolUri != null) 'uri': serviceProtocolUri,
  +      if (appSizeBase != null) 'appSizeBase': appSizeBase,
  +      if (appSizeTest != null) 'appSizeTest': appSizeTest,
  +    };
  +    String url = Uri.parse(devToolsUrl)
  +        .replace(queryParameters: queryParameters)
  +        .toString();
  +
  +    // If app size parameters are present, open to the standalone `appsize`
  +    // page, regardless if there is a vm service uri specified. We only check
  +    // for the presence of [appSizeBase] here because [appSizeTest] may or may
  +    // not be specified (it should only be present for diffs). If [appSizeTest]
  +    // is present without [appSizeBase], we will ignore the parameter.
  +    if (appSizeBase != null) {
  +      final startQueryParamIndex = url.indexOf('?');
  +      if (startQueryParamIndex != -1) {
  +        url = '${url.substring(0, startQueryParamIndex)}'
  +            '/#/appsize'
  +            '${url.substring(startQueryParamIndex)}';
  +      }
       }
   
       try {
  
positive.code: const argVmUri = 'vm-uri';
  const argEnableNotifications = 'enable-notifications';
  const argAllowEmbedding = 'allow-embedding';
  const argHeadlessMode = 'headless';
  const argDebugMode = 'debug';
  const argLaunchBrowser = 'launch-browser';
  
negative.code:       argProfileMemoryOld,
        defaultsTo: 'memory_samples.json',
        hide: true,
      )
      ..addOption(
        argAppSizeBase,
        valueHelp: 'appSizeBase',
        help: 'Path to the base app size file used for app size debugging.',
        hide: true,
      )
      ..addOption(
        argAppSizeTest,
        valueHelp: 'appSizeTest',
        help: 'Path to the test app size file used for app size debugging. This '
            'file should only be specified if a base app size file (appSizeBase) '
            'is also specified.',
        hide: true,
      );
  
    // Args to show for verbose mode.
  