flutter_web_platform.dart 22.5 KB
Newer Older
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141
// Copyright 2019 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// ignore_for_file: implementation_imports

import 'dart:async';

import 'package:async/async.dart';
import 'package:http_multi_server/http_multi_server.dart';
import 'package:path/path.dart' as p; // ignore: package_path_import
import 'package:pool/pool.dart';
import 'package:shelf/shelf.dart' as shelf;
import 'package:shelf/shelf_io.dart' as shelf_io;
import 'package:shelf_packages_handler/shelf_packages_handler.dart';
import 'package:shelf_static/shelf_static.dart';
import 'package:shelf_web_socket/shelf_web_socket.dart';
import 'package:stream_channel/stream_channel.dart';
import 'package:test_api/backend.dart';
import 'package:test_api/src/backend/runtime.dart';
import 'package:test_api/src/backend/suite_platform.dart';
import 'package:test_api/src/util/stack_trace_mapper.dart';
import 'package:test_core/src/runner/configuration.dart';
import 'package:test_core/src/runner/environment.dart';
import 'package:test_core/src/runner/platform.dart';
import 'package:test_core/src/runner/plugin/platform_helpers.dart';
import 'package:test_core/src/runner/runner_suite.dart';
import 'package:test_core/src/runner/suite.dart';
import 'package:web_socket_channel/web_socket_channel.dart';

import '../artifacts.dart';
import '../base/common.dart';
import '../base/file_system.dart';
import '../cache.dart';
import '../convert.dart';
import '../dart/package_map.dart';
import '../globals.dart';
import '../web/chrome.dart';

class FlutterWebPlatform extends PlatformPlugin {
  FlutterWebPlatform._(this._server, this._config, this._root) {
    // Look up the location of the testing resources.
    final Map<String, Uri> packageMap = PackageMap(fs.path.join(
      Cache.flutterRoot,
      'packages',
      'flutter_tools',
      '.packages',
    )).map;
    testUri = packageMap['test'];
    final shelf.Cascade cascade = shelf.Cascade()
        .add(_webSocketHandler.handler)
        .add(packagesDirHandler())
        .add(_jsHandler.handler)
        .add(createStaticHandler(
          fs.path.join(Cache.flutterRoot, 'packages', 'flutter_tools'),
          serveFilesOutsidePath: true,
        ))
        .add(createStaticHandler(_config.suiteDefaults.precompiledPath,
            serveFilesOutsidePath: true))
        .add(_handleStaticArtifact)
        .add(_wrapperHandler);
    _server.mount(cascade.handler);
  }

  static Future<FlutterWebPlatform> start(String root) async {
    final shelf_io.IOServer server =
        shelf_io.IOServer(await HttpMultiServer.loopback(0));
    return FlutterWebPlatform._(
      server,
      Configuration.current,
      root,
    );
  }

  Uri testUri;

  /// The test runner configuration.
  final Configuration _config;

  /// The underlying server.
  final shelf.Server _server;

  /// The URL for this server.
  Uri get url => _server.url;

  /// The ahem text file.
  File get ahem => fs.file(fs.path.join(
        Cache.flutterRoot,
        'packages',
        'flutter_tools',
        'static',
        'Ahem.ttf',
      ));

  /// The require js binary.
  File get requireJs => fs.file(fs.path.join(
        artifacts.getArtifactPath(Artifact.engineDartSdkPath),
        'lib',
        'dev_compiler',
        'amd',
        'require.js',
      ));

  /// The ddc to dart stack trace mapper.
  File get stackTraceMapper => fs.file(fs.path.join(
        artifacts.getArtifactPath(Artifact.engineDartSdkPath),
        'lib',
        'dev_compiler',
        'web',
        'dart_stack_trace_mapper.js',
      ));

  /// The precompiled dart sdk.
  File get dartSdk => fs.file(fs.path.join(
        artifacts.getArtifactPath(Artifact.flutterWebSdk),
        'kernel',
        'amd',
        'dart_sdk.js',
      ));

  /// The precompiled test javascript.
  File get testDartJs => fs.file(fs.path.join(
        testUri.toFilePath(),
        'dart.js',
      ));

  File get testHostDartJs => fs.file(fs.path.join(
        testUri.toFilePath(),
        'src',
        'runner',
        'browser',
        'static',
        'host.dart.js',
      ));

  Future<shelf.Response> _handleStaticArtifact(shelf.Request request) async {
    if (request.requestedUri.path.contains('require.js')) {
      return shelf.Response.ok(
        requireJs.openRead(),
        headers: <String, String>{'Content-Type': 'text/javascript'},
      );
142
    } else if (request.requestedUri.path.contains('ahem.ttf')) {
143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207
      return shelf.Response.ok(ahem.openRead());
    } else if (request.requestedUri.path.contains('dart_sdk.js')) {
      return shelf.Response.ok(
        dartSdk.openRead(),
        headers: <String, String>{'Content-Type': 'text/javascript'},
      );
    } else if (request.requestedUri.path
        .contains('stack_trace_mapper.dart.js')) {
      return shelf.Response.ok(
        stackTraceMapper.openRead(),
        headers: <String, String>{'Content-Type': 'text/javascript'},
      );
    } else if (request.requestedUri.path.contains('static/dart.js')) {
      return shelf.Response.ok(
        testDartJs.openRead(),
        headers: <String, String>{'Content-Type': 'text/javascript'},
      );
    } else if (request.requestedUri.path.contains('host.dart.js')) {
      return shelf.Response.ok(
        testHostDartJs.openRead(),
        headers: <String, String>{'Content-Type': 'text/javascript'},
      );
    } else {
      return shelf.Response.notFound('Not Found');
    }
  }

  final OneOffHandler _webSocketHandler = OneOffHandler();
  final PathHandler _jsHandler = PathHandler();
  final AsyncMemoizer<void> _closeMemo = AsyncMemoizer<void>();
  final String _root;

  bool get _closed => _closeMemo.hasRun;

  // A map from browser identifiers to futures that will complete to the
  // [BrowserManager]s for those browsers, or `null` if they failed to load.
  final Map<Runtime, Future<BrowserManager>> _browserManagers =
      <Runtime, Future<BrowserManager>>{};

  // Mappers for Dartifying stack traces, indexed by test path.
  final Map<String, StackTraceMapper> _mappers = <String, StackTraceMapper>{};

  // A handler that serves wrapper files used to bootstrap tests.
  shelf.Response _wrapperHandler(shelf.Request request) {
    final String path = fs.path.fromUri(request.url);
    if (path.endsWith('.html')) {
      final String test = fs.path.withoutExtension(path) + '.dart';
      final String scriptBase = htmlEscape.convert(fs.path.basename(test));
      final String link = '<link rel="x-dart-test" href="$scriptBase">';
      return shelf.Response.ok('''
        <!DOCTYPE html>
        <html>
        <head>
          <title>${htmlEscape.convert(test)} Test</title>
          $link
          <script src="static/dart.js"></script>
        </head>
        </html>
      ''', headers: <String, String>{'Content-Type': 'text/html'});
    }
    printTrace('Did not find anything for request: ${request.url}');
    return shelf.Response.notFound('Not found.');
  }

  @override
208 209 210 211 212 213
  Future<RunnerSuite> load(
    String path,
    SuitePlatform platform,
    SuiteConfiguration suiteConfig,
    Object message,
  ) async {
214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251
    if (_closed) {
      return null;
    }
    final Runtime browser = platform.runtime;
    final BrowserManager browserManager = await _browserManagerFor(browser);
    if (_closed || browserManager == null) {
      return null;
    }

    final Uri suiteUrl = url.resolveUri(fs.path.toUri(fs.path.withoutExtension(
            fs.path.relative(path, from: fs.path.join(_root, 'test'))) +
        '.html'));
    final RunnerSuite suite = await browserManager
        .load(path, suiteUrl, suiteConfig, message, mapper: _mappers[path]);
    if (_closed) {
      return null;
    }
    return suite;
  }

  @override
  StreamChannel<dynamic> loadChannel(String path, SuitePlatform platform) =>
      throw UnimplementedError();

  /// Returns the [BrowserManager] for [runtime], which should be a browser.
  ///
  /// If no browser manager is running yet, starts one.
  Future<BrowserManager> _browserManagerFor(Runtime browser) {
    final Future<BrowserManager> managerFuture = _browserManagers[browser];
    if (managerFuture != null) {
      return managerFuture;
    }
    final Completer<WebSocketChannel> completer =
        Completer<WebSocketChannel>.sync();
    final String path =
        _webSocketHandler.create(webSocketHandler(completer.complete));
    final Uri webSocketUrl = url.replace(scheme: 'ws').resolve(path);
    final Uri hostUrl = url
252 253 254 255 256
      .resolve('static/index.html')
      .replace(queryParameters: <String, String>{
        'managerUrl': webSocketUrl.toString(),
        'debug': _config.pauseAfterLoad.toString(),
      });
257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288

    printTrace('Serving tests at $hostUrl');

    final Future<BrowserManager> future = BrowserManager.start(
      browser,
      hostUrl,
      completer.future,
    );

    // Store null values for browsers that error out so we know not to load them
    // again.
    _browserManagers[browser] = future.catchError((dynamic _) => null);

    return future;
  }

  @override
  Future<void> closeEphemeral() {
    final List<Future<BrowserManager>> managers =
        _browserManagers.values.toList();
    _browserManagers.clear();
    return Future.wait(managers.map((Future<BrowserManager> manager) async {
      final BrowserManager result = await manager;
      if (result == null) {
        return;
      }
      await result.close();
    }));
  }

  @override
  Future<void> close() => _closeMemo.runOnce(() async {
289 290 291 292 293 294 295 296 297 298 299 300
    final List<Future<dynamic>> futures = _browserManagers.values
      .map<Future<dynamic>>((Future<BrowserManager> future) async {
        final BrowserManager result = await future;
        if (result == null) {
          return;
        }
        await result.close();
      })
      .toList();
    futures.add(_server.close());
    await Future.wait<void>(futures);
  });
301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418
}

class OneOffHandler {
  /// A map from URL paths to handlers.
  final Map<String, shelf.Handler> _handlers = <String, shelf.Handler>{};

  /// The counter of handlers that have been activated.
  int _counter = 0;

  /// The actual [shelf.Handler] that dispatches requests.
  shelf.Handler get handler => _onRequest;

  /// Creates a new one-off handler that forwards to [handler].
  ///
  /// Returns a string that's the URL path for hitting this handler, relative to
  /// the URL for the one-off handler itself.
  ///
  /// [handler] will be unmounted as soon as it receives a request.
  String create(shelf.Handler handler) {
    final String path = _counter.toString();
    _handlers[path] = handler;
    _counter++;
    return path;
  }

  /// Dispatches [request] to the appropriate handler.
  FutureOr<shelf.Response> _onRequest(shelf.Request request) {
    final List<String> components = p.url.split(request.url.path);
    if (components.isEmpty) {
      return shelf.Response.notFound(null);
    }
    final String path = components.removeAt(0);
    final FutureOr<shelf.Response> Function(shelf.Request) handler =
        _handlers.remove(path);
    if (handler == null) {
      return shelf.Response.notFound(null);
    }
    return handler(request.change(path: path));
  }
}

class PathHandler {
  /// A trie of path components to handlers.
  final _Node _paths = _Node();

  /// The shelf handler.
  shelf.Handler get handler => _onRequest;

  /// Returns middleware that nests all requests beneath the URL prefix
  /// [beneath].
  static shelf.Middleware nestedIn(String beneath) {
    return (FutureOr<shelf.Response> Function(shelf.Request) handler) {
      final PathHandler pathHandler = PathHandler()..add(beneath, handler);
      return pathHandler.handler;
    };
  }

  /// Routes requests at or under [path] to [handler].
  ///
  /// If [path] is a parent or child directory of another path in this handler,
  /// the longest matching prefix wins.
  void add(String path, shelf.Handler handler) {
    _Node node = _paths;
    for (String component in p.url.split(path)) {
      node = node.children.putIfAbsent(component, () => _Node());
    }
    node.handler = handler;
  }

  FutureOr<shelf.Response> _onRequest(shelf.Request request) {
    shelf.Handler handler;
    int handlerIndex;
    _Node node = _paths;
    final List<String> components = p.url.split(request.url.path);
    for (int i = 0; i < components.length; i++) {
      node = node.children[components[i]];
      if (node == null) {
        break;
      }
      if (node.handler == null) {
        continue;
      }
      handler = node.handler;
      handlerIndex = i;
    }

    if (handler == null) {
      return shelf.Response.notFound('Not found.');
    }

    return handler(
        request.change(path: p.url.joinAll(components.take(handlerIndex + 1))));
  }
}

/// A trie node.
class _Node {
  shelf.Handler handler;
  final Map<String, _Node> children = <String, _Node>{};
}

class BrowserManager {
  /// Creates a new BrowserManager that communicates with [browser] over
  /// [webSocket].
  BrowserManager._(this._browser, this._runtime, WebSocketChannel webSocket) {
    // The duration should be short enough that the debugging console is open as
    // soon as the user is done setting breakpoints, but long enough that a test
    // doing a lot of synchronous work doesn't trigger a false positive.
    //
    // Start this canceled because we don't want it to start ticking until we
    // get some response from the iframe.
    _timer = RestartableTimer(const Duration(seconds: 3), () {
      for (RunnerSuiteController controller in _controllers) {
        controller.setDebugging(true);
      }
    })
      ..cancel();

419 420
    // Whenever we get a message, no matter which child channel it's for, we know
    // the browser is still running code which means the user isn't debugging.
421
    _channel = MultiChannel<dynamic>(
422 423 424 425 426 427 428 429
      webSocket.cast<String>().transform(jsonDocument).changeStream((Stream<Object> stream) {
        return stream.map((Object message) {
          if (!_closed) {
            _timer.reset();
          }
          for (RunnerSuiteController controller in _controllers) {
            controller.setDebugging(false);
          }
430

431 432 433 434
          return message;
        });
      }),
    );
435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459

    _environment = _loadBrowserEnvironment();
    _channel.stream.listen(_onMessage, onDone: close);
  }

  /// The browser instance that this is connected to via [_channel].
  final Chrome _browser;

  // TODO(nweiz): Consider removing the duplication between this and
  // [_browser.name].
  /// The [Runtime] for [_browser].
  final Runtime _runtime;

  /// The channel used to communicate with the browser.
  ///
  /// This is connected to a page running `static/host.dart`.
  MultiChannel<dynamic> _channel;

  /// A pool that ensures that limits the number of initial connections the
  /// manager will wait for at once.
  ///
  /// This isn't the *total* number of connections; any number of iframes may be
  /// loaded in the same browser. However, the browser can only load so many at
  /// once, and we want a timeout in case they fail so we only wait for so many
  /// at once.
460 461 462 463 464 465 466
  // The number 1 is chosen to disallow multiple iframes in the same browser. This
  // is because in some environments, such as Cirrus CI, tests end up stuck and
  // time out eventually. The exact reason for timeouts is unknown, but the
  // hypothesis is that we were the first ones to attempt to run DDK-compiled
  // tests concurrently in the browser. DDK is known to produce an order of
  // magnitude bigger and somewhat slower code, which may overload the browser.
  final Pool _pool = Pool(1);
467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515

  /// The ID of the next suite to be loaded.
  ///
  /// This is used to ensure that the suites can be referred to consistently
  /// across the client and server.
  int _suiteID = 0;

  /// Whether the channel to the browser has closed.
  bool _closed = false;

  /// The completer for [_BrowserEnvironment.displayPause].
  ///
  /// This will be `null` as long as the browser isn't displaying a pause
  /// screen.
  CancelableCompleter<dynamic> _pauseCompleter;

  /// The controller for [_BrowserEnvironment.onRestart].
  final StreamController<dynamic> _onRestartController =
      StreamController<dynamic>.broadcast();

  /// The environment to attach to each suite.
  Future<_BrowserEnvironment> _environment;

  /// Controllers for every suite in this browser.
  ///
  /// These are used to mark suites as debugging or not based on the browser's
  /// pings.
  final Set<RunnerSuiteController> _controllers = <RunnerSuiteController>{};

  // A timer that's reset whenever we receive a message from the browser.
  //
  // Because the browser stops running code when the user is actively debugging,
  // this lets us detect whether they're debugging reasonably accurately.
  RestartableTimer _timer;

  final AsyncMemoizer<dynamic> _closeMemoizer = AsyncMemoizer<dynamic>();

  /// Starts the browser identified by [runtime] and has it connect to [url].
  ///
  /// [url] should serve a page that establishes a WebSocket connection with
  /// this process. That connection, once established, should be emitted via
  /// [future]. If [debug] is true, starts the browser in debug mode, with its
  /// debugger interfaces on and detected.
  ///
  /// The [settings] indicate how to invoke this browser's executable.
  ///
  /// Returns the browser manager, or throws an [ApplicationException] if a
  /// connection fails to be established.
  static Future<BrowserManager> start(
516 517 518 519 520
    Runtime runtime,
    Uri url,
    Future<WebSocketChannel> future, {
    bool debug = false,
  }) async {
521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559
    final Chrome chrome =
        await chromeLauncher.launch(url.toString(), headless: true);

    final Completer<BrowserManager> completer = Completer<BrowserManager>();

    unawaited(chrome.onExit.then((void _) {
      throwToolExit('${runtime.name} exited before connecting.');
    }).catchError((dynamic error, StackTrace stackTrace) {
      if (completer.isCompleted) {
        return;
      }
      completer.completeError(error, stackTrace);
    }));
    unawaited(future.then((WebSocketChannel webSocket) {
      if (completer.isCompleted) {
        return;
      }
      completer.complete(BrowserManager._(chrome, runtime, webSocket));
    }).catchError((dynamic error, StackTrace stackTrace) {
      chrome.close();
      if (completer.isCompleted) {
        return;
      }
      completer.completeError(error, stackTrace);
    }));

    return completer.future.timeout(const Duration(seconds: 30), onTimeout: () {
      chrome.close();
      throwToolExit('Timed out waiting for ${runtime.name} to connect.');
      return;
    });
  }

  /// Loads [_BrowserEnvironment].
  Future<_BrowserEnvironment> _loadBrowserEnvironment() async {
    return _BrowserEnvironment(
        this, null, _browser.remoteDebuggerUri, _onRestartController.stream);
  }

560
  /// Tells the browser to load a test suite from the URL [url].
561 562 563 564 565 566 567 568
  ///
  /// [url] should be an HTML page with a reference to the JS-compiled test
  /// suite. [path] is the path of the original test suite file, which is used
  /// for reporting. [suiteConfig] is the configuration for the test suite.
  ///
  /// If [mapper] is passed, it's used to map stack traces for errors coming
  /// from this test suite.
  Future<RunnerSuite> load(
569 570 571 572 573 574
    String path,
    Uri url,
    SuiteConfiguration suiteConfig,
    Object message, {
    StackTraceMapper mapper,
  }) async {
575
    url = url.replace(fragment: Uri.encodeFull(jsonEncode(<String, Object>{
576
      'metadata': suiteConfig.metadata.serialize(),
577
      'browser': _runtime.identifier,
578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595
    })));

    final int suiteID = _suiteID++;
    RunnerSuiteController controller;
    void closeIframe() {
      if (_closed) {
        return;
      }
      _controllers.remove(controller);
      _channel.sink
          .add(<String, Object>{'command': 'closeSuite', 'id': suiteID});
    }

    // The virtual channel will be closed when the suite is closed, in which
    // case we should unload the iframe.
    final VirtualChannel<dynamic> virtualChannel = _channel.virtualChannel();
    final int suiteChannelID = virtualChannel.id;
    final StreamChannel<dynamic> suiteChannel = virtualChannel.transformStream(
596 597 598 599 600
      StreamTransformer<dynamic, dynamic>.fromHandlers(handleDone: (EventSink<dynamic> sink) {
        closeIframe();
        sink.close();
      }),
    );
601 602 603 604 605 606

    return await _pool.withResource<RunnerSuite>(() async {
      _channel.sink.add(<String, Object>{
        'command': 'loadSuite',
        'url': url.toString(),
        'id': suiteID,
607
        'channel': suiteChannelID,
608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680
      });

      try {
        controller = deserializeSuite(path, SuitePlatform(Runtime.chrome),
            suiteConfig, await _environment, suiteChannel, message);
        controller.channel('test.browser.mapper').sink.add(mapper?.serialize());

        _controllers.add(controller);
        return await controller.suite;
      } catch (_) {
        closeIframe();
        rethrow;
      }
    });
  }

  /// An implementation of [Environment.displayPause].
  CancelableOperation<dynamic> _displayPause() {
    if (_pauseCompleter != null) {
      return _pauseCompleter.operation;
    }
    _pauseCompleter = CancelableCompleter<dynamic>(onCancel: () {
      _channel.sink.add(<String, String>{'command': 'resume'});
      _pauseCompleter = null;
    });
    _pauseCompleter.operation.value.whenComplete(() {
      _pauseCompleter = null;
    });
    _channel.sink.add(<String, String>{'command': 'displayPause'});

    return _pauseCompleter.operation;
  }

  /// The callback for handling messages received from the host page.
  void _onMessage(dynamic message) {
    switch (message['command'] as String) {
      case 'ping':
        break;
      case 'restart':
        _onRestartController.add(null);
        break;
      case 'resume':
        if (_pauseCompleter != null) {
          _pauseCompleter.complete();
        }
        break;
      default:
        // Unreachable.
        assert(false);
        break;
    }
  }

  /// Closes the manager and releases any resources it owns, including closing
  /// the browser.
  Future<dynamic> close() {
    return _closeMemoizer.runOnce(() {
      _closed = true;
      _timer.cancel();
      if (_pauseCompleter != null) {
        _pauseCompleter.complete();
      }
      _pauseCompleter = null;
      _controllers.clear();
      return _browser.close();
    });
  }
}

/// An implementation of [Environment] for the browser.
///
/// All methods forward directly to [BrowserManager].
class _BrowserEnvironment implements Environment {
681 682 683 684 685 686
  _BrowserEnvironment(
    this._manager,
    this.observatoryUrl,
    this.remoteDebuggerUrl,
    this.onRestart,
  );
687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704

  final BrowserManager _manager;

  @override
  final bool supportsDebugging = true;

  @override
  final Uri observatoryUrl;

  @override
  final Uri remoteDebuggerUrl;

  @override
  final Stream<dynamic> onRestart;

  @override
  CancelableOperation<dynamic> displayPause() => _manager._displayPause();
}