packages/flutter_tools/lib/src/web/chrome.dart - external/github.com/flutter/flutter - Git at Google

 // Copyright 2014 The Flutter Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.

 import 'dart:async';

 import 'package:meta/meta.dart';
 import 'package:process/process.dart';
 import 'package:webkit_inspection_protocol/webkit_inspection_protocol.dart';

 import '../base/common.dart';
 import '../base/file_system.dart';
 import '../base/io.dart';
 import '../base/logger.dart';
 import '../base/os.dart';
 import '../base/platform.dart';
 import '../convert.dart';

 /// An environment variable used to override the location of Google Chrome.
 const String kChromeEnvironment = 'CHROME_EXECUTABLE';

 /// An environment variable used to override the location of Microsoft Edge.
 const String kEdgeEnvironment = 'EDGE_ENVIRONMENT';

 /// The expected executable name on linux.
 const String kLinuxExecutable = 'google-chrome';

 /// The expected executable name on macOS.
 const String kMacOSExecutable =
     '/Applications/Google Chrome.app/Contents/MacOS/Google Chrome';

 /// The expected Chrome executable name on Windows.
 const String kWindowsExecutable = r'Google\Chrome\Application\chrome.exe';

 /// The expected Edge executable name on Windows.
 const String kWindowsEdgeExecutable = r'Microsoft\Edge\Application\msedge.exe';

 /// Used by [ChromiumLauncher] to detect a glibc bug and retry launching the
 /// browser.
 ///
 /// Once every few thousands of launches we hit this glibc bug:
 ///
 /// https://sourceware.org/bugzilla/show_bug.cgi?id=19329.
 ///
 /// When this happens Chrome spits out something like the following then exits with code 127:
 ///
 ///     Inconsistency detected by ld.so: ../elf/dl-tls.c: 493: _dl_allocate_tls_init: Assertion `listp->slotinfo[cnt].gen <= GL(dl_tls_generation)' failed!
 const String _kGlibcError = 'Inconsistency detected by ld.so';

 typedef BrowserFinder = String Function(Platform, FileSystem);

 /// Find the chrome executable on the current platform.
 ///
 /// Does not verify whether the executable exists.
 String findChromeExecutable(Platform platform, FileSystem fileSystem) {
   if (platform.environment.containsKey(kChromeEnvironment)) {
     return platform.environment[kChromeEnvironment];
   }
   if (platform.isLinux) {
     return kLinuxExecutable;
   }
   if (platform.isMacOS) {
     return kMacOSExecutable;
   }
   if (platform.isWindows) {
     /// The possible locations where the chrome executable can be located on windows.
     final List<String> kWindowsPrefixes = <String>[
       platform.environment['LOCALAPPDATA'],
       platform.environment['PROGRAMFILES'],
       platform.environment['PROGRAMFILES(X86)'],
     ];
     final String windowsPrefix = kWindowsPrefixes.firstWhere((String prefix) {
       if (prefix == null) {
         return false;
       }
       final String path = fileSystem.path.join(prefix, kWindowsExecutable);
       return fileSystem.file(path).existsSync();
     }, orElse: () => '.');
     return fileSystem.path.join(windowsPrefix, kWindowsExecutable);
   }
   throwToolExit('Platform ${platform.operatingSystem} is not supported.');
   return null;
 }

 /// Find the Microsoft Edge executable on the current platform.
 ///
 /// Does not verify whether the executable exists.
 String findEdgeExecutable(Platform platform, FileSystem fileSystem) {
   if (platform.environment.containsKey(kEdgeEnvironment)) {
     return platform.environment[kEdgeEnvironment];
   }
   if (platform.isWindows) {
     /// The possible locations where the Edge executable can be located on windows.
     final List<String> kWindowsPrefixes = <String>[
       platform.environment['LOCALAPPDATA'],
       platform.environment['PROGRAMFILES'],
       platform.environment['PROGRAMFILES(X86)'],
     ];
     final String windowsPrefix = kWindowsPrefixes.firstWhere((String prefix) {
       if (prefix == null) {
         return false;
       }
       final String path = fileSystem.path.join(prefix, kWindowsEdgeExecutable);
       return fileSystem.file(path).existsSync();
     }, orElse: () => '.');
     return fileSystem.path.join(windowsPrefix, kWindowsEdgeExecutable);
   }
   // Not yet supported for macOS and Linux.
   return '';
 }

 /// A launcher for Chromium browsers with devtools configured.
 class ChromiumLauncher {
   ChromiumLauncher({
     @required FileSystem fileSystem,
     @required Platform platform,
     @required ProcessManager processManager,
     @required OperatingSystemUtils operatingSystemUtils,
     @required BrowserFinder browserFinder,
     @required Logger logger,
     @visibleForTesting FileSystemUtils fileSystemUtils,
   }) : _fileSystem = fileSystem,
        _platform = platform,
        _processManager = processManager,
        _operatingSystemUtils = operatingSystemUtils,
        _browserFinder = browserFinder,
        _logger = logger,
        _fileSystemUtils = fileSystemUtils ?? FileSystemUtils(
          fileSystem: fileSystem,
          platform: platform,
        );

   final FileSystem _fileSystem;
   final Platform _platform;
   final ProcessManager _processManager;
   final OperatingSystemUtils _operatingSystemUtils;
   final BrowserFinder _browserFinder;
   final FileSystemUtils _fileSystemUtils;
   final Logger _logger;

   bool get hasChromeInstance => _currentCompleter.isCompleted;

   Completer<Chromium> _currentCompleter = Completer<Chromium>();

   @visibleForTesting
   void testLaunchChromium(Chromium chromium) {
     _currentCompleter.complete(chromium);
   }

   /// Whether we can locate the chrome executable.
   bool canFindExecutable() {
     final String chrome = _browserFinder(_platform, _fileSystem);
     try {
       return _processManager.canRun(chrome);
     } on ArgumentError {
       return false;
     }
   }

   /// The executable this launcher will use.
   String findExecutable() =>  _browserFinder(_platform, _fileSystem);

   /// Launch a Chromium browser to a particular `host` page.
   ///
   /// [headless] defaults to false, and controls whether we open a headless or
   /// a "headfull" browser.
   ///
   /// [debugPort] is Chrome's debugging protocol port. If null, a random free
   /// port is picked automatically.
   ///
   /// [skipCheck] does not attempt to make a devtools connection before returning.
   Future<Chromium> launch(String url, {
     bool headless = false,
     int debugPort,
     bool skipCheck = false,
     Directory cacheDir,
   }) async {
     if (_currentCompleter.isCompleted) {
       throwToolExit('Only one instance of chrome can be started.');
     }

     final String chromeExecutable = _browserFinder(_platform, _fileSystem);

     if (_logger.isVerbose) {
       final ProcessResult versionResult = await _processManager.run(<String>[chromeExecutable, '--version']);
       _logger.printTrace('Using ${versionResult.stdout}');
     }

     final Directory userDataDir = _fileSystem.systemTempDirectory
       .createTempSync('flutter_tools_chrome_device.');

     if (cacheDir != null) {
       // Seed data dir with previous state.
       _restoreUserSessionInformation(cacheDir, userDataDir);
     }

     final int port = debugPort ?? await _operatingSystemUtils.findFreePort();
     final List<String> args = <String>[
       chromeExecutable,
       // Using a tmp directory ensures that a new instance of chrome launches
       // allowing for the remote debug port to be enabled.
       '--user-data-dir=${userDataDir.path}',
       '--remote-debugging-port=$port',
       // When the DevTools has focus we don't want to slow down the application.
       '--disable-background-timer-throttling',
       // Since we are using a temp profile, disable features that slow the
       // Chrome launch.
       '--disable-extensions',
       '--disable-popup-blocking',
       '--bwsi',
       '--no-first-run',
       '--no-default-browser-check',
       '--disable-default-apps',
       '--disable-translate',
       if (headless)
         ...<String>[
           '--headless',
           '--disable-gpu',
           '--no-sandbox',
           '--window-size=2400,1800',
         ],
       url,
     ];

     final Process process = await _spawnChromiumProcess(args);

     // When the process exits, copy the user settings back to the provided data-dir.
     if (cacheDir != null) {
       unawaited(process.exitCode.whenComplete(() {
         _cacheUserSessionInformation(userDataDir, cacheDir);
       }));
     }
     return _connect(Chromium._(
       port,
       ChromeConnection('localhost', port),
       url: url,
       process: process,
       chromiumLauncher: this,
     ), skipCheck);
   }

   Future<Process> _spawnChromiumProcess(List<String> args) async {
     // Keep attempting to launch the browser until one of:
     // - Chrome launched successfully, in which case we just return from the loop.
     // - The tool detected an unretriable Chrome error, in which case we throw ToolExit.
     while (true) {
       final Process process = await _processManager.start(args);

       process.stdout
         .transform(utf8.decoder)
         .transform(const LineSplitter())
         .listen((String line) {
           _logger.printTrace('[CHROME]: $line');
         });

       // Wait until the DevTools are listening before trying to connect. This is
       // only required for flutter_test --platform=chrome and not flutter run.
       bool hitGlibcBug = false;
       await process.stderr
         .transform(utf8.decoder)
         .transform(const LineSplitter())
         .map((String line) {
           _logger.printTrace('[CHROME]:$line');
           if (line.contains(_kGlibcError)) {
             hitGlibcBug = true;
           }
           return line;
         })
         .firstWhere((String line) => line.startsWith('DevTools listening'), orElse: () {
           if (hitGlibcBug) {
             _logger.printTrace(
               'Encountered glibc bug https://sourceware.org/bugzilla/show_bug.cgi?id=19329. '
               'Will try launching browser again.',
             );
             return null;
           }
           _logger.printTrace('Failed to launch browser. Command used to launch it: ${args.join(' ')}');
           throw ToolExit(
             'Failed to launch browser. Make sure you are using an up-to-date '
             'Chrome or Edge. Otherwise, consider using -d web-server instead '
             'and filing an issue at https://github.com/flutter/flutter/issues.',
           );
         });

       if (!hitGlibcBug) {
         return process;
       }

       // A precaution that avoids accumulating browser processes, in case the
       // glibc bug doesn't cause the browser to quit and we keep looping and
       // launching more processes.
       unawaited(process.exitCode.timeout(const Duration(seconds: 1), onTimeout: () {
         process.kill();
         return null;
       }));
     }
   }

   // This is a JSON file which contains configuration from the browser session,
   // such as window position. It is located under the Chrome data-dir folder.
   String get _preferencesPath => _fileSystem.path.join('Default', 'preferences');

   // The directory that Chrome uses to store local storage information for web apps.
   String get _localStoragePath => _fileSystem.path.join('Default', 'Local Storage');

   /// Copy Chrome user information from a Chrome session into a per-project
   /// cache.
   ///
   /// Note: more detailed docs of the Chrome user preferences store exists here:
   /// https://www.chromium.org/developers/design-documents/preferences.
   void _cacheUserSessionInformation(Directory userDataDir, Directory cacheDir) {
     final File targetPreferencesFile = _fileSystem.file(_fileSystem.path.join(cacheDir?.path ?? '', _preferencesPath));
     final File sourcePreferencesFile = _fileSystem.file(_fileSystem.path.join(userDataDir.path, _preferencesPath));
     final Directory targetLocalStorageDir = _fileSystem.directory(_fileSystem.path.join(cacheDir?.path ?? '', _localStoragePath));
     final Directory sourceLocalStorageDir = _fileSystem.directory(_fileSystem.path.join(userDataDir.path, _localStoragePath));

     if (sourcePreferencesFile.existsSync()) {
       targetPreferencesFile.parent.createSync(recursive: true);
       // If the file contains a crash string, remove it to hide the popup on next run.
       final String contents = sourcePreferencesFile.readAsStringSync();
       targetPreferencesFile.writeAsStringSync(contents
           .replaceFirst('"exit_type":"Crashed"', '"exit_type":"Normal"'));
     }

     if (sourceLocalStorageDir.existsSync()) {
       targetLocalStorageDir.createSync(recursive: true);
       try {
         _fileSystemUtils.copyDirectorySync(sourceLocalStorageDir, targetLocalStorageDir);
       } on FileSystemException catch (err) {
         // This is a best-effort update. Display the message in case the failure is relevant.
         // one possible example is a file lock due to multiple running chrome instances.
         _logger.printError('Failed to save Chrome preferences: $err');
       }
     }
   }

   /// Restore Chrome user information from a per-project cache into Chrome's
   /// user data directory.
   void _restoreUserSessionInformation(Directory cacheDir, Directory userDataDir) {
     final File sourcePreferencesFile = _fileSystem.file(_fileSystem.path.join(cacheDir.path ?? '', _preferencesPath));
     final File targetPreferencesFile = _fileSystem.file(_fileSystem.path.join(userDataDir.path, _preferencesPath));
     final Directory sourceLocalStorageDir = _fileSystem.directory(_fileSystem.path.join(cacheDir.path ?? '', _localStoragePath));
     final Directory targetLocalStorageDir = _fileSystem.directory(_fileSystem.path.join(userDataDir.path, _localStoragePath));

     if (sourcePreferencesFile.existsSync()) {
       targetPreferencesFile.parent.createSync(recursive: true);
       sourcePreferencesFile.copySync(targetPreferencesFile.path);
     }

     if (sourceLocalStorageDir.existsSync()) {
       targetLocalStorageDir.createSync(recursive: true);
       _fileSystemUtils.copyDirectorySync(sourceLocalStorageDir, targetLocalStorageDir);
     }
   }

   Future<Chromium> _connect(Chromium chrome, bool skipCheck) async {
     // The connection is lazy. Try a simple call to make sure the provided
     // connection is valid.
     if (!skipCheck) {
       try {
         await chrome.chromeConnection.getTabs();
       } on Exception catch (e) {
         await chrome.close();
         throwToolExit(
             'Unable to connect to Chrome debug port: ${chrome.debugPort}\n $e');
       }
     }
     _currentCompleter.complete(chrome);
     return chrome;
   }

   Future<Chromium> get connectedInstance => _currentCompleter.future;
 }

 /// A class for managing an instance of a Chromium browser.
 class Chromium {
   Chromium._(
     this.debugPort,
     this.chromeConnection, {
     this.url,
     Process process,
     @required ChromiumLauncher chromiumLauncher,
   })  : _process = process,
         _chromiumLauncher = chromiumLauncher;

   final String url;
   final int debugPort;
   final Process _process;
   final ChromeConnection chromeConnection;
   final ChromiumLauncher _chromiumLauncher;

   Future<int> get onExit => _process.exitCode;

   Future<void> close() async {
     if (_chromiumLauncher.hasChromeInstance) {
       _chromiumLauncher._currentCompleter = Completer<Chromium>();
     }
     chromeConnection.close();
     _process?.kill();
     await _process?.exitCode;
   }
 }
	// Copyright 2014 The Flutter Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style license that can be
	// found in the LICENSE file.

	import 'dart:async';

	import 'package:meta/meta.dart';
	import 'package:process/process.dart';
	import 'package:webkit_inspection_protocol/webkit_inspection_protocol.dart';

	import '../base/common.dart';
	import '../base/file_system.dart';
	import '../base/io.dart';
	import '../base/logger.dart';
	import '../base/os.dart';
	import '../base/platform.dart';
	import '../convert.dart';

	/// An environment variable used to override the location of Google Chrome.
	const String kChromeEnvironment = 'CHROME_EXECUTABLE';

	/// An environment variable used to override the location of Microsoft Edge.
	const String kEdgeEnvironment = 'EDGE_ENVIRONMENT';

	/// The expected executable name on linux.
	const String kLinuxExecutable = 'google-chrome';

	/// The expected executable name on macOS.
	const String kMacOSExecutable =
	'/Applications/Google Chrome.app/Contents/MacOS/Google Chrome';

	/// The expected Chrome executable name on Windows.
	const String kWindowsExecutable = r'Google\Chrome\Application\chrome.exe';

	/// The expected Edge executable name on Windows.
	const String kWindowsEdgeExecutable = r'Microsoft\Edge\Application\msedge.exe';

	/// Used by [ChromiumLauncher] to detect a glibc bug and retry launching the
	/// browser.
	///
	/// Once every few thousands of launches we hit this glibc bug:
	///
	/// https://sourceware.org/bugzilla/show_bug.cgi?id=19329.
	///
	/// When this happens Chrome spits out something like the following then exits with code 127:
	///
	/// Inconsistency detected by ld.so: ../elf/dl-tls.c: 493: _dl_allocate_tls_init: Assertion `listp->slotinfo[cnt].gen <= GL(dl_tls_generation)' failed!
	const String _kGlibcError = 'Inconsistency detected by ld.so';

	typedef BrowserFinder = String Function(Platform, FileSystem);

	/// Find the chrome executable on the current platform.
	///
	/// Does not verify whether the executable exists.
	String findChromeExecutable(Platform platform, FileSystem fileSystem) {
	if (platform.environment.containsKey(kChromeEnvironment)) {
	return platform.environment[kChromeEnvironment];
	}
	if (platform.isLinux) {
	return kLinuxExecutable;
	}
	if (platform.isMacOS) {
	return kMacOSExecutable;
	}
	if (platform.isWindows) {
	/// The possible locations where the chrome executable can be located on windows.
	final List<String> kWindowsPrefixes = <String>[
	platform.environment['LOCALAPPDATA'],
	platform.environment['PROGRAMFILES'],
	platform.environment['PROGRAMFILES(X86)'],
	];
	final String windowsPrefix = kWindowsPrefixes.firstWhere((String prefix) {
	if (prefix == null) {
	return false;
	}
	final String path = fileSystem.path.join(prefix, kWindowsExecutable);
	return fileSystem.file(path).existsSync();
	}, orElse: () => '.');
	return fileSystem.path.join(windowsPrefix, kWindowsExecutable);
	}
	throwToolExit('Platform ${platform.operatingSystem} is not supported.');
	return null;
	}

	/// Find the Microsoft Edge executable on the current platform.
	///
	/// Does not verify whether the executable exists.
	String findEdgeExecutable(Platform platform, FileSystem fileSystem) {
	if (platform.environment.containsKey(kEdgeEnvironment)) {
	return platform.environment[kEdgeEnvironment];
	}
	if (platform.isWindows) {
	/// The possible locations where the Edge executable can be located on windows.
	final List<String> kWindowsPrefixes = <String>[
	platform.environment['LOCALAPPDATA'],
	platform.environment['PROGRAMFILES'],
	platform.environment['PROGRAMFILES(X86)'],
	];
	final String windowsPrefix = kWindowsPrefixes.firstWhere((String prefix) {
	if (prefix == null) {
	return false;
	}
	final String path = fileSystem.path.join(prefix, kWindowsEdgeExecutable);
	return fileSystem.file(path).existsSync();
	}, orElse: () => '.');
	return fileSystem.path.join(windowsPrefix, kWindowsEdgeExecutable);
	}
	// Not yet supported for macOS and Linux.
	return '';
	}

	/// A launcher for Chromium browsers with devtools configured.
	class ChromiumLauncher {
	ChromiumLauncher({
	@required FileSystem fileSystem,
	@required Platform platform,
	@required ProcessManager processManager,
	@required OperatingSystemUtils operatingSystemUtils,
	@required BrowserFinder browserFinder,
	@required Logger logger,
	@visibleForTesting FileSystemUtils fileSystemUtils,
	}) : _fileSystem = fileSystem,
	_platform = platform,
	_processManager = processManager,
	_operatingSystemUtils = operatingSystemUtils,
	_browserFinder = browserFinder,
	_logger = logger,
	_fileSystemUtils = fileSystemUtils ?? FileSystemUtils(
	fileSystem: fileSystem,
	platform: platform,
	);

	final FileSystem _fileSystem;
	final Platform _platform;
	final ProcessManager _processManager;
	final OperatingSystemUtils _operatingSystemUtils;
	final BrowserFinder _browserFinder;
	final FileSystemUtils _fileSystemUtils;
	final Logger _logger;

	bool get hasChromeInstance => _currentCompleter.isCompleted;

	Completer<Chromium> _currentCompleter = Completer<Chromium>();

	@visibleForTesting
	void testLaunchChromium(Chromium chromium) {
	_currentCompleter.complete(chromium);
	}

	/// Whether we can locate the chrome executable.
	bool canFindExecutable() {
	final String chrome = _browserFinder(_platform, _fileSystem);
	try {
	return _processManager.canRun(chrome);
	} on ArgumentError {
	return false;
	}
	}

	/// The executable this launcher will use.
	String findExecutable() => _browserFinder(_platform, _fileSystem);

	/// Launch a Chromium browser to a particular `host` page.
	///
	/// [headless] defaults to false, and controls whether we open a headless or
	/// a "headfull" browser.
	///
	/// [debugPort] is Chrome's debugging protocol port. If null, a random free
	/// port is picked automatically.
	///
	/// [skipCheck] does not attempt to make a devtools connection before returning.
	Future<Chromium> launch(String url, {
	bool headless = false,
	int debugPort,
	bool skipCheck = false,
	Directory cacheDir,
	}) async {
	if (_currentCompleter.isCompleted) {
	throwToolExit('Only one instance of chrome can be started.');
	}

	final String chromeExecutable = _browserFinder(_platform, _fileSystem);

	if (_logger.isVerbose) {
	final ProcessResult versionResult = await _processManager.run(<String>[chromeExecutable, '--version']);
	_logger.printTrace('Using ${versionResult.stdout}');
	}

	final Directory userDataDir = _fileSystem.systemTempDirectory
	.createTempSync('flutter_tools_chrome_device.');

	if (cacheDir != null) {
	// Seed data dir with previous state.
	_restoreUserSessionInformation(cacheDir, userDataDir);
	}

	final int port = debugPort ?? await _operatingSystemUtils.findFreePort();
	final List<String> args = <String>[
	chromeExecutable,
	// Using a tmp directory ensures that a new instance of chrome launches
	// allowing for the remote debug port to be enabled.
	'--user-data-dir=${userDataDir.path}',
	'--remote-debugging-port=$port',
	// When the DevTools has focus we don't want to slow down the application.
	'--disable-background-timer-throttling',
	// Since we are using a temp profile, disable features that slow the
	// Chrome launch.
	'--disable-extensions',
	'--disable-popup-blocking',
	'--bwsi',
	'--no-first-run',
	'--no-default-browser-check',
	'--disable-default-apps',
	'--disable-translate',
	if (headless)
	...<String>[
	'--headless',
	'--disable-gpu',
	'--no-sandbox',
	'--window-size=2400,1800',
	],
	url,
	];

	final Process process = await _spawnChromiumProcess(args);

	// When the process exits, copy the user settings back to the provided data-dir.
	if (cacheDir != null) {
	unawaited(process.exitCode.whenComplete(() {
	_cacheUserSessionInformation(userDataDir, cacheDir);
	}));
	}
	return _connect(Chromium._(
	port,
	ChromeConnection('localhost', port),
	url: url,
	process: process,
	chromiumLauncher: this,
	), skipCheck);
	}

	Future<Process> _spawnChromiumProcess(List<String> args) async {
	// Keep attempting to launch the browser until one of:
	// - Chrome launched successfully, in which case we just return from the loop.
	// - The tool detected an unretriable Chrome error, in which case we throw ToolExit.
	while (true) {
	final Process process = await _processManager.start(args);

	process.stdout
	.transform(utf8.decoder)
	.transform(const LineSplitter())
	.listen((String line) {
	_logger.printTrace('[CHROME]: $line');
	});

	// Wait until the DevTools are listening before trying to connect. This is
	// only required for flutter_test --platform=chrome and not flutter run.
	bool hitGlibcBug = false;
	await process.stderr
	.transform(utf8.decoder)
	.transform(const LineSplitter())
	.map((String line) {
	_logger.printTrace('[CHROME]:$line');
	if (line.contains(_kGlibcError)) {
	hitGlibcBug = true;
	}
	return line;
	})
	.firstWhere((String line) => line.startsWith('DevTools listening'), orElse: () {
	if (hitGlibcBug) {
	_logger.printTrace(
	'Encountered glibc bug https://sourceware.org/bugzilla/show_bug.cgi?id=19329. '
	'Will try launching browser again.',
	);
	return null;
	}
	_logger.printTrace('Failed to launch browser. Command used to launch it: ${args.join(' ')}');
	throw ToolExit(
	'Failed to launch browser. Make sure you are using an up-to-date '
	'Chrome or Edge. Otherwise, consider using -d web-server instead '
	'and filing an issue at https://github.com/flutter/flutter/issues.',
	);
	});

	if (!hitGlibcBug) {
	return process;
	}

	// A precaution that avoids accumulating browser processes, in case the
	// glibc bug doesn't cause the browser to quit and we keep looping and
	// launching more processes.
	unawaited(process.exitCode.timeout(const Duration(seconds: 1), onTimeout: () {
	process.kill();
	return null;
	}));
	}
	}

	// This is a JSON file which contains configuration from the browser session,
	// such as window position. It is located under the Chrome data-dir folder.
	String get _preferencesPath => _fileSystem.path.join('Default', 'preferences');

	// The directory that Chrome uses to store local storage information for web apps.
	String get _localStoragePath => _fileSystem.path.join('Default', 'Local Storage');

	/// Copy Chrome user information from a Chrome session into a per-project
	/// cache.
	///
	/// Note: more detailed docs of the Chrome user preferences store exists here:
	/// https://www.chromium.org/developers/design-documents/preferences.
	void _cacheUserSessionInformation(Directory userDataDir, Directory cacheDir) {
	final File targetPreferencesFile = _fileSystem.file(_fileSystem.path.join(cacheDir?.path ?? '', _preferencesPath));
	final File sourcePreferencesFile = _fileSystem.file(_fileSystem.path.join(userDataDir.path, _preferencesPath));
	final Directory targetLocalStorageDir = _fileSystem.directory(_fileSystem.path.join(cacheDir?.path ?? '', _localStoragePath));
	final Directory sourceLocalStorageDir = _fileSystem.directory(_fileSystem.path.join(userDataDir.path, _localStoragePath));

	if (sourcePreferencesFile.existsSync()) {
	targetPreferencesFile.parent.createSync(recursive: true);
	// If the file contains a crash string, remove it to hide the popup on next run.
	final String contents = sourcePreferencesFile.readAsStringSync();
	targetPreferencesFile.writeAsStringSync(contents
	.replaceFirst('"exit_type":"Crashed"', '"exit_type":"Normal"'));
	}

	if (sourceLocalStorageDir.existsSync()) {
	targetLocalStorageDir.createSync(recursive: true);
	try {
	_fileSystemUtils.copyDirectorySync(sourceLocalStorageDir, targetLocalStorageDir);
	} on FileSystemException catch (err) {
	// This is a best-effort update. Display the message in case the failure is relevant.
	// one possible example is a file lock due to multiple running chrome instances.
	_logger.printError('Failed to save Chrome preferences: $err');
	}
	}
	}

	/// Restore Chrome user information from a per-project cache into Chrome's
	/// user data directory.
	void _restoreUserSessionInformation(Directory cacheDir, Directory userDataDir) {
	final File sourcePreferencesFile = _fileSystem.file(_fileSystem.path.join(cacheDir.path ?? '', _preferencesPath));
	final File targetPreferencesFile = _fileSystem.file(_fileSystem.path.join(userDataDir.path, _preferencesPath));
	final Directory sourceLocalStorageDir = _fileSystem.directory(_fileSystem.path.join(cacheDir.path ?? '', _localStoragePath));
	final Directory targetLocalStorageDir = _fileSystem.directory(_fileSystem.path.join(userDataDir.path, _localStoragePath));

	if (sourcePreferencesFile.existsSync()) {
	targetPreferencesFile.parent.createSync(recursive: true);
	sourcePreferencesFile.copySync(targetPreferencesFile.path);
	}

	if (sourceLocalStorageDir.existsSync()) {
	targetLocalStorageDir.createSync(recursive: true);
	_fileSystemUtils.copyDirectorySync(sourceLocalStorageDir, targetLocalStorageDir);
	}
	}

	Future<Chromium> _connect(Chromium chrome, bool skipCheck) async {
	// The connection is lazy. Try a simple call to make sure the provided
	// connection is valid.
	if (!skipCheck) {
	try {
	await chrome.chromeConnection.getTabs();
	} on Exception catch (e) {
	await chrome.close();
	throwToolExit(
	'Unable to connect to Chrome debug port: ${chrome.debugPort}\n $e');
	}
	}
	_currentCompleter.complete(chrome);
	return chrome;
	}

	Future<Chromium> get connectedInstance => _currentCompleter.future;
	}

	/// A class for managing an instance of a Chromium browser.
	class Chromium {
	Chromium._(
	this.debugPort,
	this.chromeConnection, {
	this.url,
	Process process,
	@required ChromiumLauncher chromiumLauncher,
	}) : _process = process,
	_chromiumLauncher = chromiumLauncher;

	final String url;
	final int debugPort;
	final Process _process;
	final ChromeConnection chromeConnection;
	final ChromiumLauncher _chromiumLauncher;

	Future<int> get onExit => _process.exitCode;

	Future<void> close() async {
	if (_chromiumLauncher.hasChromeInstance) {
	_chromiumLauncher._currentCompleter = Completer<Chromium>();
	}
	chromeConnection.close();
	_process?.kill();
	await _process?.exitCode;
	}
	}