From a440899880829bafddbfa61dacaad66c33e288d4 Mon Sep 17 00:00:00 2001
From: Harry Terkelsen <het@google.com>
Date: Fri, 18 Oct 2019 13:53:32 -0700
Subject: [PATCH 01/10] [url_launcher] Add overridable platform

---
 .../url_launcher/url_launcher/CHANGELOG.md    |  5 ++
 .../lib/method_channel_url_launcher.dart      | 47 +++++++++++++
 .../url_launcher/lib/url_launcher.dart        | 49 +++++++++-----
 .../lib/url_launcher_platform_interface.dart  | 29 ++++++++
 .../url_launcher/url_launcher/pubspec.yaml    |  2 +-
 .../test/url_launcher_platform_test.dart      | 67 +++++++++++++++++++
 6 files changed, 181 insertions(+), 18 deletions(-)
 create mode 100644 packages/url_launcher/url_launcher/lib/method_channel_url_launcher.dart
 create mode 100644 packages/url_launcher/url_launcher/lib/url_launcher_platform_interface.dart
 create mode 100644 packages/url_launcher/url_launcher/test/url_launcher_platform_test.dart

diff --git a/packages/url_launcher/url_launcher/CHANGELOG.md b/packages/url_launcher/url_launcher/CHANGELOG.md
index 9893c4f8931d..f4f48ae0feb6 100644
--- a/packages/url_launcher/url_launcher/CHANGELOG.md
+++ b/packages/url_launcher/url_launcher/CHANGELOG.md
@@ -1,3 +1,8 @@
+## 5.2.3
+
+* Adds `urlLauncherPlatform` which can be overridden to implement `url_launcher`
+  on other platforms (which may not want to use MethodChannels).
+
 ## 5.2.2
 
 * Re-land embedder v2 support with correct Flutter SDK constraints.
diff --git a/packages/url_launcher/url_launcher/lib/method_channel_url_launcher.dart b/packages/url_launcher/url_launcher/lib/method_channel_url_launcher.dart
new file mode 100644
index 000000000000..4beb4098bde9
--- /dev/null
+++ b/packages/url_launcher/url_launcher/lib/method_channel_url_launcher.dart
@@ -0,0 +1,47 @@
+import 'dart:async';
+
+import 'package:flutter/services.dart';
+
+import 'url_launcher_platform_interface.dart';
+
+const MethodChannel _channel = MethodChannel('plugins.flutter.io/url_launcher');
+
+/// An implementation of [UrlLauncherPlatform] that uses method channels.
+class MethodChannelUrlLauncher extends UrlLauncherPlatform {
+  @override
+  Future<bool> canLaunch(String url) {
+    return _channel.invokeMethod<bool>(
+      'canLaunch',
+      <String, Object>{'url': url},
+    );
+  }
+
+  @override
+  Future<void> closeWebView() {
+    return _channel.invokeMethod<void>('closeWebView');
+  }
+
+  @override
+  Future<bool> launch(
+    String url,
+    bool useSafariVC,
+    bool useWebView,
+    bool enableJavaScript,
+    bool enableDomStorage,
+    bool universalLinksOnly,
+    Map<String, String> headers,
+  ) {
+    _channel.invokeMethod<bool>(
+      'launch',
+      <String, Object>{
+        'url': url,
+        'useSafariVC': useSafariVC,
+        'useWebView': useWebView,
+        'enableJavaScript': enableJavaScript,
+        'enableDomStorage': enableDomStorage,
+        'universalLinksOnly': universalLinksOnly,
+        'headers': headers,
+      },
+    );
+  }
+}
diff --git a/packages/url_launcher/url_launcher/lib/url_launcher.dart b/packages/url_launcher/url_launcher/lib/url_launcher.dart
index 045448fbde97..51bcc5875c2b 100644
--- a/packages/url_launcher/url_launcher/lib/url_launcher.dart
+++ b/packages/url_launcher/url_launcher/lib/url_launcher.dart
@@ -8,7 +8,8 @@ import 'package:flutter/foundation.dart';
 import 'package:flutter/services.dart';
 import 'package:flutter/widgets.dart';
 
-const MethodChannel _channel = MethodChannel('plugins.flutter.io/url_launcher');
+import 'url_launcher_platform_interface.dart';
+import 'method_channel_url_launcher.dart';
 
 /// Parses the specified URL string and delegates handling of it to the
 /// underlying platform.
@@ -84,17 +85,14 @@ Future<bool> launch(
         ? SystemUiOverlayStyle.dark
         : SystemUiOverlayStyle.light);
   }
-  final bool result = await _channel.invokeMethod<bool>(
-    'launch',
-    <String, Object>{
-      'url': urlString,
-      'useSafariVC': forceSafariVC ?? isWebURL,
-      'useWebView': forceWebView ?? false,
-      'enableJavaScript': enableJavaScript ?? false,
-      'enableDomStorage': enableDomStorage ?? false,
-      'universalLinksOnly': universalLinksOnly ?? false,
-      'headers': headers ?? <String, String>{},
-    },
+  final bool result = await urlLauncherPlatform.launch(
+    urlString,
+    forceSafariVC ?? isWebURL,
+    forceWebView ?? false,
+    enableJavaScript ?? false,
+    enableDomStorage ?? false,
+    universalLinksOnly ?? false,
+    headers ?? <String, String>{},
   );
   if (statusBarBrightness != null) {
     WidgetsBinding.instance.renderView.automaticSystemUiAdjustment =
@@ -109,10 +107,7 @@ Future<bool> canLaunch(String urlString) async {
   if (urlString == null) {
     return false;
   }
-  return await _channel.invokeMethod<bool>(
-    'canLaunch',
-    <String, Object>{'url': urlString},
-  );
+  return await urlLauncherPlatform.canLaunch(urlString);
 }
 
 /// Closes the current WebView, if one was previously opened via a call to [launch].
@@ -127,5 +122,25 @@ Future<bool> canLaunch(String urlString) async {
 /// SafariViewController is only available on IOS version >= 9.0, this method does not do anything
 /// on IOS version below 9.0
 Future<void> closeWebView() async {
-  return await _channel.invokeMethod<void>('closeWebView');
+  return await urlLauncherPlatform.closeWebView();
+}
+
+UrlLauncherPlatform _platform;
+
+/// The [UrlLauncherPlatform] that will do the platform-specific work.
+///
+/// Defaults to [MethodChannelUrlLauncher].
+UrlLauncherPlatform get urlLauncherPlatform {
+  if (_platform == null) {
+    _platform = MethodChannelUrlLauncher();
+  }
+  return _platform;
+}
+
+/// Sets the [UrlLauncherPlatform] to use.
+///
+/// Set the platform if you have a platform-specific implementation of
+/// [UrlLauncherPlatform] that you would like to use.
+set urlLauncherPlatform(UrlLauncherPlatform newPlatform) {
+  _platform = newPlatform;
 }
diff --git a/packages/url_launcher/url_launcher/lib/url_launcher_platform_interface.dart b/packages/url_launcher/url_launcher/lib/url_launcher_platform_interface.dart
new file mode 100644
index 000000000000..ffe8e883a6c3
--- /dev/null
+++ b/packages/url_launcher/url_launcher/lib/url_launcher_platform_interface.dart
@@ -0,0 +1,29 @@
+// Copyright 2017 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.
+
+import 'dart:async';
+
+/// The interface that implementations of url_launcher must implement.
+abstract class UrlLauncherPlatform {
+  /// Returns `true` if this platform is able to launch [url].
+  Future<bool> canLaunch(String url);
+
+  /// Returns `true` if the given [url] was successfully launched.
+  ///
+  /// For documentation on the other arguments, see the `launch` documentation
+  /// in `package:url_launcher/url_launcher.dart`.
+  Future<bool> launch(
+      String url,
+      bool useSafariVC,
+      bool useWebView,
+      bool enableJavaScript,
+      bool enableDomStorage,
+      bool universalLinksOnly,
+      Map<String, String> headers,
+  );
+
+
+  /// Closes the WebView, if one was opened earlier by `launch`.
+  Future<void> closeWebView();
+}
diff --git a/packages/url_launcher/url_launcher/pubspec.yaml b/packages/url_launcher/url_launcher/pubspec.yaml
index 6f882fbc740a..4763469d558d 100644
--- a/packages/url_launcher/url_launcher/pubspec.yaml
+++ b/packages/url_launcher/url_launcher/pubspec.yaml
@@ -3,7 +3,7 @@ description: Flutter plugin for launching a URL on Android and iOS. Supports
   web, phone, SMS, and email schemes.
 author: Flutter Team <flutter-dev@googlegroups.com>
 homepage: https://github.com/flutter/plugins/tree/master/packages/url_launcher/url_launcher
-version: 5.2.2
+version: 5.2.3
 
 flutter:
   plugin:
diff --git a/packages/url_launcher/url_launcher/test/url_launcher_platform_test.dart b/packages/url_launcher/url_launcher/test/url_launcher_platform_test.dart
new file mode 100644
index 000000000000..2a5466e59bf2
--- /dev/null
+++ b/packages/url_launcher/url_launcher/test/url_launcher_platform_test.dart
@@ -0,0 +1,67 @@
+// Copyright 2017 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.
+
+import 'package:flutter_test/flutter_test.dart';
+import 'package:url_launcher/url_launcher.dart';
+import 'package:url_launcher/url_launcher_platform_interface.dart';
+
+void main() {
+  TestWidgetsFlutterBinding.ensureInitialized();
+
+  group('UrlLauncher with mock platform', () {
+    final MockUrlLauncherPlatform platform = MockUrlLauncherPlatform();
+    urlLauncherPlatform = platform;
+
+    test('can mock "canLaunch"', () async {
+      expect(canLaunch('http://www.google.com'), completion(isFalse));
+
+      platform.launchableUrls.add('http://www.google.com');
+
+      expect(canLaunch('http://www.google.com'), completion(isTrue));
+
+      platform.launchableUrls.clear();
+    });
+
+    test('can mock "launch"', () async {
+      expect(launch('http://www.google.com'), completion(isFalse));
+
+      platform.launchableUrls.add('http://www.google.com');
+
+      expect(launch('http://www.google.com'), completion(isTrue));
+
+      platform.launchableUrls.clear();
+    });
+
+    test('can mock "closeWebView"', () async {
+      expect(closeWebView(), completes);
+    });
+  });
+}
+
+class MockUrlLauncherPlatform extends UrlLauncherPlatform {
+  Set<String> launchableUrls = Set<String>();
+
+  @override
+  Future<bool> canLaunch(String url) {
+    return Future.value(launchableUrls.contains(url));
+  }
+
+  @override
+  Future<void> closeWebView() {
+    return Future<void>.value();
+  }
+
+  @override
+  Future<bool> launch(
+    String url,
+    bool useSafariVC,
+    bool useWebView,
+    bool enableJavaScript,
+    bool enableDomStorage,
+    bool universalLinksOnly,
+    Map<String, String> headers,
+  ) {
+    return Future.value(launchableUrls.contains(url));
+  }
+}

From d1f0ca2cd893a4c5d6dabd931ee3ef5f840187c3 Mon Sep 17 00:00:00 2001
From: Harry Terkelsen <het@google.com>
Date: Fri, 18 Oct 2019 13:59:46 -0700
Subject: [PATCH 02/10] Fix analyzer lints

---
 .../url_launcher/lib/method_channel_url_launcher.dart    | 2 +-
 packages/url_launcher/url_launcher/lib/url_launcher.dart | 2 +-
 .../url_launcher/test/url_launcher_platform_test.dart    | 9 +++++++--
 3 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/packages/url_launcher/url_launcher/lib/method_channel_url_launcher.dart b/packages/url_launcher/url_launcher/lib/method_channel_url_launcher.dart
index 4beb4098bde9..74da123a90ad 100644
--- a/packages/url_launcher/url_launcher/lib/method_channel_url_launcher.dart
+++ b/packages/url_launcher/url_launcher/lib/method_channel_url_launcher.dart
@@ -31,7 +31,7 @@ class MethodChannelUrlLauncher extends UrlLauncherPlatform {
     bool universalLinksOnly,
     Map<String, String> headers,
   ) {
-    _channel.invokeMethod<bool>(
+    return _channel.invokeMethod<bool>(
       'launch',
       <String, Object>{
         'url': url,
diff --git a/packages/url_launcher/url_launcher/lib/url_launcher.dart b/packages/url_launcher/url_launcher/lib/url_launcher.dart
index 51bcc5875c2b..7173d86d59ec 100644
--- a/packages/url_launcher/url_launcher/lib/url_launcher.dart
+++ b/packages/url_launcher/url_launcher/lib/url_launcher.dart
@@ -8,8 +8,8 @@ import 'package:flutter/foundation.dart';
 import 'package:flutter/services.dart';
 import 'package:flutter/widgets.dart';
 
-import 'url_launcher_platform_interface.dart';
 import 'method_channel_url_launcher.dart';
+import 'url_launcher_platform_interface.dart';
 
 /// Parses the specified URL string and delegates handling of it to the
 /// underlying platform.
diff --git a/packages/url_launcher/url_launcher/test/url_launcher_platform_test.dart b/packages/url_launcher/url_launcher/test/url_launcher_platform_test.dart
index 2a5466e59bf2..05de983e41ba 100644
--- a/packages/url_launcher/url_launcher/test/url_launcher_platform_test.dart
+++ b/packages/url_launcher/url_launcher/test/url_launcher_platform_test.dart
@@ -40,11 +40,16 @@ void main() {
 }
 
 class MockUrlLauncherPlatform extends UrlLauncherPlatform {
+  // Ignoring the `prefer_collection_literals` warning here because if we use
+  // a set literal, it will give another warning saying this code is required
+  // to run on versions of Dart that are older than 2.2 (when set literals were
+  // added.
+  // ignore: prefer_collection_literals
   Set<String> launchableUrls = Set<String>();
 
   @override
   Future<bool> canLaunch(String url) {
-    return Future.value(launchableUrls.contains(url));
+    return Future<bool>.value(launchableUrls.contains(url));
   }
 
   @override
@@ -62,6 +67,6 @@ class MockUrlLauncherPlatform extends UrlLauncherPlatform {
     bool universalLinksOnly,
     Map<String, String> headers,
   ) {
-    return Future.value(launchableUrls.contains(url));
+    return Future<bool>.value(launchableUrls.contains(url));
   }
 }

From d58d524ca54cd5dae3f800b217e8bf71745689ea Mon Sep 17 00:00:00 2001
From: Harry Terkelsen <het@google.com>
Date: Fri, 18 Oct 2019 14:52:24 -0700
Subject: [PATCH 03/10] Run dartfmt

---
 .../lib/url_launcher_platform_interface.dart      | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/packages/url_launcher/url_launcher/lib/url_launcher_platform_interface.dart b/packages/url_launcher/url_launcher/lib/url_launcher_platform_interface.dart
index ffe8e883a6c3..865df02ad2d7 100644
--- a/packages/url_launcher/url_launcher/lib/url_launcher_platform_interface.dart
+++ b/packages/url_launcher/url_launcher/lib/url_launcher_platform_interface.dart
@@ -14,16 +14,15 @@ abstract class UrlLauncherPlatform {
   /// For documentation on the other arguments, see the `launch` documentation
   /// in `package:url_launcher/url_launcher.dart`.
   Future<bool> launch(
-      String url,
-      bool useSafariVC,
-      bool useWebView,
-      bool enableJavaScript,
-      bool enableDomStorage,
-      bool universalLinksOnly,
-      Map<String, String> headers,
+    String url,
+    bool useSafariVC,
+    bool useWebView,
+    bool enableJavaScript,
+    bool enableDomStorage,
+    bool universalLinksOnly,
+    Map<String, String> headers,
   );
 
-
   /// Closes the WebView, if one was opened earlier by `launch`.
   Future<void> closeWebView();
 }

From bada3feca40764d34b0b652f502eb70f05e7bc81 Mon Sep 17 00:00:00 2001
From: Harry Terkelsen <het@google.com>
Date: Tue, 22 Oct 2019 10:39:50 -0700
Subject: [PATCH 04/10] Add a url_launcher_platform_interface package

---
 .../url_launcher/url_launcher/CHANGELOG.md    |  5 --
 .../url_launcher/lib/url_launcher.dart        | 49 +++++++------------
 .../url_launcher/url_launcher/pubspec.yaml    |  2 +-
 .../url_launcher_platform_interface/README.md | 19 +++++++
 .../lib/method_channel_url_launcher.dart      |  0
 .../lib/url_launcher_platform_interface.dart  |  0
 .../pubspec.yaml                              | 19 +++++++
 .../test/url_launcher_platform_test.dart      |  2 +-
 8 files changed, 57 insertions(+), 39 deletions(-)
 create mode 100644 packages/url_launcher/url_launcher_platform_interface/README.md
 rename packages/url_launcher/{url_launcher => url_launcher_platform_interface}/lib/method_channel_url_launcher.dart (100%)
 rename packages/url_launcher/{url_launcher => url_launcher_platform_interface}/lib/url_launcher_platform_interface.dart (100%)
 create mode 100644 packages/url_launcher/url_launcher_platform_interface/pubspec.yaml
 rename packages/url_launcher/{url_launcher => url_launcher_platform_interface}/test/url_launcher_platform_test.dart (95%)

diff --git a/packages/url_launcher/url_launcher/CHANGELOG.md b/packages/url_launcher/url_launcher/CHANGELOG.md
index f4f48ae0feb6..9893c4f8931d 100644
--- a/packages/url_launcher/url_launcher/CHANGELOG.md
+++ b/packages/url_launcher/url_launcher/CHANGELOG.md
@@ -1,8 +1,3 @@
-## 5.2.3
-
-* Adds `urlLauncherPlatform` which can be overridden to implement `url_launcher`
-  on other platforms (which may not want to use MethodChannels).
-
 ## 5.2.2
 
 * Re-land embedder v2 support with correct Flutter SDK constraints.
diff --git a/packages/url_launcher/url_launcher/lib/url_launcher.dart b/packages/url_launcher/url_launcher/lib/url_launcher.dart
index 7173d86d59ec..045448fbde97 100644
--- a/packages/url_launcher/url_launcher/lib/url_launcher.dart
+++ b/packages/url_launcher/url_launcher/lib/url_launcher.dart
@@ -8,8 +8,7 @@ import 'package:flutter/foundation.dart';
 import 'package:flutter/services.dart';
 import 'package:flutter/widgets.dart';
 
-import 'method_channel_url_launcher.dart';
-import 'url_launcher_platform_interface.dart';
+const MethodChannel _channel = MethodChannel('plugins.flutter.io/url_launcher');
 
 /// Parses the specified URL string and delegates handling of it to the
 /// underlying platform.
@@ -85,14 +84,17 @@ Future<bool> launch(
         ? SystemUiOverlayStyle.dark
         : SystemUiOverlayStyle.light);
   }
-  final bool result = await urlLauncherPlatform.launch(
-    urlString,
-    forceSafariVC ?? isWebURL,
-    forceWebView ?? false,
-    enableJavaScript ?? false,
-    enableDomStorage ?? false,
-    universalLinksOnly ?? false,
-    headers ?? <String, String>{},
+  final bool result = await _channel.invokeMethod<bool>(
+    'launch',
+    <String, Object>{
+      'url': urlString,
+      'useSafariVC': forceSafariVC ?? isWebURL,
+      'useWebView': forceWebView ?? false,
+      'enableJavaScript': enableJavaScript ?? false,
+      'enableDomStorage': enableDomStorage ?? false,
+      'universalLinksOnly': universalLinksOnly ?? false,
+      'headers': headers ?? <String, String>{},
+    },
   );
   if (statusBarBrightness != null) {
     WidgetsBinding.instance.renderView.automaticSystemUiAdjustment =
@@ -107,7 +109,10 @@ Future<bool> canLaunch(String urlString) async {
   if (urlString == null) {
     return false;
   }
-  return await urlLauncherPlatform.canLaunch(urlString);
+  return await _channel.invokeMethod<bool>(
+    'canLaunch',
+    <String, Object>{'url': urlString},
+  );
 }
 
 /// Closes the current WebView, if one was previously opened via a call to [launch].
@@ -122,25 +127,5 @@ Future<bool> canLaunch(String urlString) async {
 /// SafariViewController is only available on IOS version >= 9.0, this method does not do anything
 /// on IOS version below 9.0
 Future<void> closeWebView() async {
-  return await urlLauncherPlatform.closeWebView();
-}
-
-UrlLauncherPlatform _platform;
-
-/// The [UrlLauncherPlatform] that will do the platform-specific work.
-///
-/// Defaults to [MethodChannelUrlLauncher].
-UrlLauncherPlatform get urlLauncherPlatform {
-  if (_platform == null) {
-    _platform = MethodChannelUrlLauncher();
-  }
-  return _platform;
-}
-
-/// Sets the [UrlLauncherPlatform] to use.
-///
-/// Set the platform if you have a platform-specific implementation of
-/// [UrlLauncherPlatform] that you would like to use.
-set urlLauncherPlatform(UrlLauncherPlatform newPlatform) {
-  _platform = newPlatform;
+  return await _channel.invokeMethod<void>('closeWebView');
 }
diff --git a/packages/url_launcher/url_launcher/pubspec.yaml b/packages/url_launcher/url_launcher/pubspec.yaml
index 4763469d558d..6f882fbc740a 100644
--- a/packages/url_launcher/url_launcher/pubspec.yaml
+++ b/packages/url_launcher/url_launcher/pubspec.yaml
@@ -3,7 +3,7 @@ description: Flutter plugin for launching a URL on Android and iOS. Supports
   web, phone, SMS, and email schemes.
 author: Flutter Team <flutter-dev@googlegroups.com>
 homepage: https://github.com/flutter/plugins/tree/master/packages/url_launcher/url_launcher
-version: 5.2.3
+version: 5.2.2
 
 flutter:
   plugin:
diff --git a/packages/url_launcher/url_launcher_platform_interface/README.md b/packages/url_launcher/url_launcher_platform_interface/README.md
new file mode 100644
index 000000000000..d7d3ac0cded2
--- /dev/null
+++ b/packages/url_launcher/url_launcher_platform_interface/README.md
@@ -0,0 +1,19 @@
+# url_launcher_platform_interface
+
+A common platform interface for the [`url_launcher`][1] plugin.
+
+This interface allows platform-specific implementations of the `url_launcher`
+plugin, as well as the plugin itself, to ensure they are supporting the
+same interface.
+
+# Usage
+
+To implement a new platform-specific implementation of `url_launcher`, you can
+either implement the method channel calls (specified in
+[`method_channel_url_launcher.dart`][2]) or you can implement your own instance
+of [`UrlLauncherPlatform`][3] and register it with `package:url_launcher` by
+setting `urlLauncherPlatform`.
+
+[1]: ../url_launcher
+[2]: lib/method_channel_url_launcher.dart
+[3]: lib/url_launcher_platform_interface.dart
diff --git a/packages/url_launcher/url_launcher/lib/method_channel_url_launcher.dart b/packages/url_launcher/url_launcher_platform_interface/lib/method_channel_url_launcher.dart
similarity index 100%
rename from packages/url_launcher/url_launcher/lib/method_channel_url_launcher.dart
rename to packages/url_launcher/url_launcher_platform_interface/lib/method_channel_url_launcher.dart
diff --git a/packages/url_launcher/url_launcher/lib/url_launcher_platform_interface.dart b/packages/url_launcher/url_launcher_platform_interface/lib/url_launcher_platform_interface.dart
similarity index 100%
rename from packages/url_launcher/url_launcher/lib/url_launcher_platform_interface.dart
rename to packages/url_launcher/url_launcher_platform_interface/lib/url_launcher_platform_interface.dart
diff --git a/packages/url_launcher/url_launcher_platform_interface/pubspec.yaml b/packages/url_launcher/url_launcher_platform_interface/pubspec.yaml
new file mode 100644
index 000000000000..1fb34e400c06
--- /dev/null
+++ b/packages/url_launcher/url_launcher_platform_interface/pubspec.yaml
@@ -0,0 +1,19 @@
+name: url_launcher_platform_interface
+description: A common platform interface for the url_launcher plugin.
+author: Flutter Team <flutter-dev@googlegroups.com>
+homepage: https://github.com/flutter/plugins/tree/master/packages/url_launcher/url_launcher_platform_interface
+version: 0.1.0
+
+dependencies:
+  flutter:
+    sdk: flutter
+
+dev_dependencies:
+  flutter_test:
+    sdk: flutter
+  url_launcher:
+    path: ../url_launcher
+
+environment:
+  sdk: ">=2.0.0-dev.28.0 <3.0.0"
+  flutter: ">=1.9.1+hotfix.4 <2.0.0"
diff --git a/packages/url_launcher/url_launcher/test/url_launcher_platform_test.dart b/packages/url_launcher/url_launcher_platform_interface/test/url_launcher_platform_test.dart
similarity index 95%
rename from packages/url_launcher/url_launcher/test/url_launcher_platform_test.dart
rename to packages/url_launcher/url_launcher_platform_interface/test/url_launcher_platform_test.dart
index 05de983e41ba..9d4c768e7ccb 100644
--- a/packages/url_launcher/url_launcher/test/url_launcher_platform_test.dart
+++ b/packages/url_launcher/url_launcher_platform_interface/test/url_launcher_platform_test.dart
@@ -4,7 +4,7 @@
 
 import 'package:flutter_test/flutter_test.dart';
 import 'package:url_launcher/url_launcher.dart';
-import 'package:url_launcher/url_launcher_platform_interface.dart';
+import 'package:url_launcher_platform_interface/url_launcher_platform_interface.dart';
 
 void main() {
   TestWidgetsFlutterBinding.ensureInitialized();

From 7cba5065bc01afe0796b03c77f1e9fd533be87a7 Mon Sep 17 00:00:00 2001
From: Harry Terkelsen <het@google.com>
Date: Tue, 22 Oct 2019 10:46:54 -0700
Subject: [PATCH 05/10] Disable tests temporarily

---
 .../test/url_launcher_platform_test.dart                   | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/packages/url_launcher/url_launcher_platform_interface/test/url_launcher_platform_test.dart b/packages/url_launcher/url_launcher_platform_interface/test/url_launcher_platform_test.dart
index 9d4c768e7ccb..e90014188048 100644
--- a/packages/url_launcher/url_launcher_platform_interface/test/url_launcher_platform_test.dart
+++ b/packages/url_launcher/url_launcher_platform_interface/test/url_launcher_platform_test.dart
@@ -9,9 +9,12 @@ import 'package:url_launcher_platform_interface/url_launcher_platform_interface.
 void main() {
   TestWidgetsFlutterBinding.ensureInitialized();
 
+  // TODO(hterkelsen): Re-enable this test once we land the corresponding
+  //     change in package:url_launcher
   group('UrlLauncher with mock platform', () {
     final MockUrlLauncherPlatform platform = MockUrlLauncherPlatform();
-    urlLauncherPlatform = platform;
+    // Skip until we add this to package:url_launcher
+    //urlLauncherPlatform = platform;
 
     test('can mock "canLaunch"', () async {
       expect(canLaunch('http://www.google.com'), completion(isFalse));
@@ -36,7 +39,7 @@ void main() {
     test('can mock "closeWebView"', () async {
       expect(closeWebView(), completes);
     });
-  });
+  }, skip: true);
 }
 
 class MockUrlLauncherPlatform extends UrlLauncherPlatform {

From 3607ed6096cc6006deef0d46100a9a1234a83e1b Mon Sep 17 00:00:00 2001
From: Harry Terkelsen <het@google.com>
Date: Tue, 22 Oct 2019 10:48:11 -0700
Subject: [PATCH 06/10] Add license header

---
 .../lib/method_channel_url_launcher.dart                      | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/packages/url_launcher/url_launcher_platform_interface/lib/method_channel_url_launcher.dart b/packages/url_launcher/url_launcher_platform_interface/lib/method_channel_url_launcher.dart
index 74da123a90ad..6e0ac187e91b 100644
--- a/packages/url_launcher/url_launcher_platform_interface/lib/method_channel_url_launcher.dart
+++ b/packages/url_launcher/url_launcher_platform_interface/lib/method_channel_url_launcher.dart
@@ -1,3 +1,7 @@
+// Copyright 2017 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.
+
 import 'dart:async';
 
 import 'package:flutter/services.dart';

From 9c33b610a2c6d6212aee1ba255ce551cfda64150 Mon Sep 17 00:00:00 2001
From: Harry Terkelsen <het@google.com>
Date: Tue, 22 Oct 2019 10:48:50 -0700
Subject: [PATCH 07/10] Fix typo in test

---
 .../test/url_launcher_platform_test.dart                        | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/url_launcher/url_launcher_platform_interface/test/url_launcher_platform_test.dart b/packages/url_launcher/url_launcher_platform_interface/test/url_launcher_platform_test.dart
index e90014188048..289dcc14352f 100644
--- a/packages/url_launcher/url_launcher_platform_interface/test/url_launcher_platform_test.dart
+++ b/packages/url_launcher/url_launcher_platform_interface/test/url_launcher_platform_test.dart
@@ -46,7 +46,7 @@ class MockUrlLauncherPlatform extends UrlLauncherPlatform {
   // Ignoring the `prefer_collection_literals` warning here because if we use
   // a set literal, it will give another warning saying this code is required
   // to run on versions of Dart that are older than 2.2 (when set literals were
-  // added.
+  // added.)
   // ignore: prefer_collection_literals
   Set<String> launchableUrls = Set<String>();
 

From e6119eed25df899f479a49356aca5e74888ee21e Mon Sep 17 00:00:00 2001
From: Harry Terkelsen <het@google.com>
Date: Tue, 22 Oct 2019 10:54:54 -0700
Subject: [PATCH 08/10] Add LICENSE file

---
 .../url_launcher_platform_interface/LICENSE   | 27 +++++++++++++++++++
 1 file changed, 27 insertions(+)
 create mode 100644 packages/url_launcher/url_launcher_platform_interface/LICENSE

diff --git a/packages/url_launcher/url_launcher_platform_interface/LICENSE b/packages/url_launcher/url_launcher_platform_interface/LICENSE
new file mode 100644
index 000000000000..c89293372cf3
--- /dev/null
+++ b/packages/url_launcher/url_launcher_platform_interface/LICENSE
@@ -0,0 +1,27 @@
+// Copyright 2017 The Chromium Authors. All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//    * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//    * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//    * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

From 732afcd49fb13d366e3e5a62bc4564e46395f6ea Mon Sep 17 00:00:00 2001
From: Harry Terkelsen <het@google.com>
Date: Tue, 22 Oct 2019 14:23:46 -0700
Subject: [PATCH 09/10] Respond to review comments

---
 .../url_launcher_platform_interface/README.md |  21 +-
 .../lib/url_launcher_platform_interface.dart  |  32 ++-
 .../pubspec.yaml                              |   4 +-
 .../method_channel_url_launcher_test.dart     | 260 ++++++++++++++++++
 .../test/url_launcher_platform_test.dart      |  75 -----
 5 files changed, 303 insertions(+), 89 deletions(-)
 create mode 100644 packages/url_launcher/url_launcher_platform_interface/test/method_channel_url_launcher_test.dart
 delete mode 100644 packages/url_launcher/url_launcher_platform_interface/test/url_launcher_platform_test.dart

diff --git a/packages/url_launcher/url_launcher_platform_interface/README.md b/packages/url_launcher/url_launcher_platform_interface/README.md
index d7d3ac0cded2..3fd6b02cfdf5 100644
--- a/packages/url_launcher/url_launcher_platform_interface/README.md
+++ b/packages/url_launcher/url_launcher_platform_interface/README.md
@@ -8,12 +8,19 @@ same interface.
 
 # Usage
 
-To implement a new platform-specific implementation of `url_launcher`, you can
-either implement the method channel calls (specified in
-[`method_channel_url_launcher.dart`][2]) or you can implement your own instance
-of [`UrlLauncherPlatform`][3] and register it with `package:url_launcher` by
-setting `urlLauncherPlatform`.
+To implement a new platform-specific implementation of `url_launcher`, extend
+[`UrlLauncherPlatform`][2] with an implementation that performs the
+platform-specific behavior, and when you register your plugin, set the default
+`UrlLauncherPlatform` by calling
+`UrlLauncherPlatform.instance = MyPlatformUrlLauncher()`.
+
+# Note on breaking changes
+
+Strongly prefer non-breaking changes (such as adding a method to the interface)
+over breaking changes for this package.
+
+See https://flutter.dev/go/platform-interface-breaking-changes for a discussion
+on why a less-clean interface is preferable to a breaking change.
 
 [1]: ../url_launcher
-[2]: lib/method_channel_url_launcher.dart
-[3]: lib/url_launcher_platform_interface.dart
+[2]: lib/url_launcher_platform_interface.dart
diff --git a/packages/url_launcher/url_launcher_platform_interface/lib/url_launcher_platform_interface.dart b/packages/url_launcher/url_launcher_platform_interface/lib/url_launcher_platform_interface.dart
index 865df02ad2d7..651a866e7403 100644
--- a/packages/url_launcher/url_launcher_platform_interface/lib/url_launcher_platform_interface.dart
+++ b/packages/url_launcher/url_launcher_platform_interface/lib/url_launcher_platform_interface.dart
@@ -4,10 +4,30 @@
 
 import 'dart:async';
 
+import 'method_channel_url_launcher.dart';
+
 /// The interface that implementations of url_launcher must implement.
+///
+/// Platform implementations that live in a separate package should extend this
+/// class rather than implement it as `url_launcher` does not consider newly
+/// added methods to be breaking changes. Extending this class (using `extends`)
+/// ensures that the subclass will get the default implementation, while
+/// platform implementations that `implements` this interface will be broken by
+/// newly added [UrlLauncherPlatform] methods.
 abstract class UrlLauncherPlatform {
+  /// The default instance of [UrlLauncherPlatform] to use.
+  ///
+  /// Platform-specific plugins should override this with their own
+  /// platform-specific class that extends [UrlLauncherPlatform] when they
+  /// register themselves.
+  ///
+  /// Defaults to [MethodChannelUrlLauncher].
+  static UrlLauncherPlatform instance = MethodChannelUrlLauncher();
+
   /// Returns `true` if this platform is able to launch [url].
-  Future<bool> canLaunch(String url);
+  Future<bool> canLaunch(String url) {
+    throw new UnimplementedError('canLaunch() has not been implemented.');
+  }
 
   /// Returns `true` if the given [url] was successfully launched.
   ///
@@ -21,8 +41,12 @@ abstract class UrlLauncherPlatform {
     bool enableDomStorage,
     bool universalLinksOnly,
     Map<String, String> headers,
-  );
+  ) {
+    throw new UnimplementedError('launch() has not been implemented.');
+  }
 
-  /// Closes the WebView, if one was opened earlier by `launch`.
-  Future<void> closeWebView();
+  /// Closes the WebView, if one was opened earlier by [launch].
+  Future<void> closeWebView() {
+    throw new UnimplementedError('closeWebView() has not been implemented.');
+  }
 }
diff --git a/packages/url_launcher/url_launcher_platform_interface/pubspec.yaml b/packages/url_launcher/url_launcher_platform_interface/pubspec.yaml
index 1fb34e400c06..ef59b68fbf44 100644
--- a/packages/url_launcher/url_launcher_platform_interface/pubspec.yaml
+++ b/packages/url_launcher/url_launcher_platform_interface/pubspec.yaml
@@ -2,7 +2,7 @@ name: url_launcher_platform_interface
 description: A common platform interface for the url_launcher plugin.
 author: Flutter Team <flutter-dev@googlegroups.com>
 homepage: https://github.com/flutter/plugins/tree/master/packages/url_launcher/url_launcher_platform_interface
-version: 0.1.0
+version: 1.0.0
 
 dependencies:
   flutter:
@@ -11,8 +11,6 @@ dependencies:
 dev_dependencies:
   flutter_test:
     sdk: flutter
-  url_launcher:
-    path: ../url_launcher
 
 environment:
   sdk: ">=2.0.0-dev.28.0 <3.0.0"
diff --git a/packages/url_launcher/url_launcher_platform_interface/test/method_channel_url_launcher_test.dart b/packages/url_launcher/url_launcher_platform_interface/test/method_channel_url_launcher_test.dart
new file mode 100644
index 000000000000..6f7651b496cd
--- /dev/null
+++ b/packages/url_launcher/url_launcher_platform_interface/test/method_channel_url_launcher_test.dart
@@ -0,0 +1,260 @@
+// Copyright 2017 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.
+
+import 'package:flutter/services.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:url_launcher_platform_interface/method_channel_url_launcher.dart';
+import 'package:url_launcher_platform_interface/url_launcher_platform_interface.dart';
+
+void main() {
+  group('$MethodChannelUrlLauncher', () {
+    TestWidgetsFlutterBinding.ensureInitialized();
+
+    const MethodChannel channel =
+        MethodChannel('plugins.flutter.io/url_launcher');
+    final List<MethodCall> log = <MethodCall>[];
+    channel.setMockMethodCallHandler((MethodCall methodCall) async {
+      log.add(methodCall);
+    });
+
+    final MethodChannelUrlLauncher launcher = MethodChannelUrlLauncher();
+
+    tearDown(() {
+      log.clear();
+    });
+
+    test('is the default $UrlLauncherPlatform instance', () {
+      expect(UrlLauncherPlatform.instance,
+          isInstanceOf<MethodChannelUrlLauncher>());
+    });
+
+    test('canLaunch', () async {
+      await launcher.canLaunch('http://example.com/');
+      expect(
+        log,
+        <Matcher>[
+          isMethodCall('canLaunch', arguments: <String, Object>{
+            'url': 'http://example.com/',
+          })
+        ],
+      );
+    });
+
+    test('launch', () async {
+      await launcher.launch(
+        'http://example.com/',
+        true,
+        false,
+        false,
+        false,
+        false,
+        const <String, String>{},
+      );
+      expect(
+        log,
+        <Matcher>[
+          isMethodCall('launch', arguments: <String, Object>{
+            'url': 'http://example.com/',
+            'useSafariVC': true,
+            'useWebView': false,
+            'enableJavaScript': false,
+            'enableDomStorage': false,
+            'universalLinksOnly': false,
+            'headers': <String, String>{},
+          })
+        ],
+      );
+    });
+
+    test('launch with headers', () async {
+      await launcher.launch(
+        'http://example.com/',
+        true,
+        false,
+        false,
+        false,
+        false,
+        const <String, String>{'key': 'value'},
+      );
+      expect(
+        log,
+        <Matcher>[
+          isMethodCall('launch', arguments: <String, Object>{
+            'url': 'http://example.com/',
+            'useSafariVC': true,
+            'useWebView': false,
+            'enableJavaScript': false,
+            'enableDomStorage': false,
+            'universalLinksOnly': false,
+            'headers': <String, String>{'key': 'value'},
+          })
+        ],
+      );
+    });
+
+    test('launch force SafariVC', () async {
+      await launcher.launch(
+        'http://example.com/',
+        true,
+        false,
+        false,
+        false,
+        false,
+        const <String, String>{},
+      );
+      expect(
+        log,
+        <Matcher>[
+          isMethodCall('launch', arguments: <String, Object>{
+            'url': 'http://example.com/',
+            'useSafariVC': true,
+            'useWebView': false,
+            'enableJavaScript': false,
+            'enableDomStorage': false,
+            'universalLinksOnly': false,
+            'headers': <String, String>{},
+          })
+        ],
+      );
+    });
+
+    test('launch universal links only', () async {
+      await launcher.launch(
+        'http://example.com/',
+        false,
+        false,
+        false,
+        false,
+        true,
+        const <String, String>{},
+      );
+      expect(
+        log,
+        <Matcher>[
+          isMethodCall('launch', arguments: <String, Object>{
+            'url': 'http://example.com/',
+            'useSafariVC': false,
+            'useWebView': false,
+            'enableJavaScript': false,
+            'enableDomStorage': false,
+            'universalLinksOnly': true,
+            'headers': <String, String>{},
+          })
+        ],
+      );
+    });
+
+    test('launch force WebView', () async {
+      await launcher.launch(
+        'http://example.com/',
+        true,
+        true,
+        false,
+        false,
+        false,
+        const <String, String>{},
+      );
+      expect(
+        log,
+        <Matcher>[
+          isMethodCall('launch', arguments: <String, Object>{
+            'url': 'http://example.com/',
+            'useSafariVC': true,
+            'useWebView': true,
+            'enableJavaScript': false,
+            'enableDomStorage': false,
+            'universalLinksOnly': false,
+            'headers': <String, String>{},
+          })
+        ],
+      );
+    });
+
+    test('launch force WebView enable javascript', () async {
+      await launcher.launch(
+        'http://example.com/',
+        true,
+        true,
+        true,
+        false,
+        false,
+        const <String, String>{},
+      );
+      expect(
+        log,
+        <Matcher>[
+          isMethodCall('launch', arguments: <String, Object>{
+            'url': 'http://example.com/',
+            'useSafariVC': true,
+            'useWebView': true,
+            'enableJavaScript': true,
+            'enableDomStorage': false,
+            'universalLinksOnly': false,
+            'headers': <String, String>{},
+          })
+        ],
+      );
+    });
+
+    test('launch force WebView enable DOM storage', () async {
+      await launcher.launch(
+        'http://example.com/',
+        true,
+        true,
+        false,
+        true,
+        false,
+        const <String, String>{},
+      );
+      expect(
+        log,
+        <Matcher>[
+          isMethodCall('launch', arguments: <String, Object>{
+            'url': 'http://example.com/',
+            'useSafariVC': true,
+            'useWebView': true,
+            'enableJavaScript': false,
+            'enableDomStorage': true,
+            'universalLinksOnly': false,
+            'headers': <String, String>{},
+          })
+        ],
+      );
+    });
+
+    test('launch force SafariVC to false', () async {
+      await launcher.launch(
+        'http://example.com/',
+        false,
+        false,
+        false,
+        false,
+        false,
+        const <String, String>{},
+      );
+      expect(
+        log,
+        <Matcher>[
+          isMethodCall('launch', arguments: <String, Object>{
+            'url': 'http://example.com/',
+            'useSafariVC': false,
+            'useWebView': false,
+            'enableJavaScript': false,
+            'enableDomStorage': false,
+            'universalLinksOnly': false,
+            'headers': <String, String>{},
+          })
+        ],
+      );
+    });
+
+    test('closeWebView default behavior', () async {
+      await launcher.closeWebView();
+      expect(
+        log,
+        <Matcher>[isMethodCall('closeWebView', arguments: null)],
+      );
+    });
+  });
+}
diff --git a/packages/url_launcher/url_launcher_platform_interface/test/url_launcher_platform_test.dart b/packages/url_launcher/url_launcher_platform_interface/test/url_launcher_platform_test.dart
deleted file mode 100644
index 289dcc14352f..000000000000
--- a/packages/url_launcher/url_launcher_platform_interface/test/url_launcher_platform_test.dart
+++ /dev/null
@@ -1,75 +0,0 @@
-// Copyright 2017 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.
-
-import 'package:flutter_test/flutter_test.dart';
-import 'package:url_launcher/url_launcher.dart';
-import 'package:url_launcher_platform_interface/url_launcher_platform_interface.dart';
-
-void main() {
-  TestWidgetsFlutterBinding.ensureInitialized();
-
-  // TODO(hterkelsen): Re-enable this test once we land the corresponding
-  //     change in package:url_launcher
-  group('UrlLauncher with mock platform', () {
-    final MockUrlLauncherPlatform platform = MockUrlLauncherPlatform();
-    // Skip until we add this to package:url_launcher
-    //urlLauncherPlatform = platform;
-
-    test('can mock "canLaunch"', () async {
-      expect(canLaunch('http://www.google.com'), completion(isFalse));
-
-      platform.launchableUrls.add('http://www.google.com');
-
-      expect(canLaunch('http://www.google.com'), completion(isTrue));
-
-      platform.launchableUrls.clear();
-    });
-
-    test('can mock "launch"', () async {
-      expect(launch('http://www.google.com'), completion(isFalse));
-
-      platform.launchableUrls.add('http://www.google.com');
-
-      expect(launch('http://www.google.com'), completion(isTrue));
-
-      platform.launchableUrls.clear();
-    });
-
-    test('can mock "closeWebView"', () async {
-      expect(closeWebView(), completes);
-    });
-  }, skip: true);
-}
-
-class MockUrlLauncherPlatform extends UrlLauncherPlatform {
-  // Ignoring the `prefer_collection_literals` warning here because if we use
-  // a set literal, it will give another warning saying this code is required
-  // to run on versions of Dart that are older than 2.2 (when set literals were
-  // added.)
-  // ignore: prefer_collection_literals
-  Set<String> launchableUrls = Set<String>();
-
-  @override
-  Future<bool> canLaunch(String url) {
-    return Future<bool>.value(launchableUrls.contains(url));
-  }
-
-  @override
-  Future<void> closeWebView() {
-    return Future<void>.value();
-  }
-
-  @override
-  Future<bool> launch(
-    String url,
-    bool useSafariVC,
-    bool useWebView,
-    bool enableJavaScript,
-    bool enableDomStorage,
-    bool universalLinksOnly,
-    Map<String, String> headers,
-  ) {
-    return Future<bool>.value(launchableUrls.contains(url));
-  }
-}

From 36d14550b8a370b56eef22aa3aa9f35e433f8db3 Mon Sep 17 00:00:00 2001
From: Harry Terkelsen <het@google.com>
Date: Tue, 22 Oct 2019 15:12:49 -0700
Subject: [PATCH 10/10] Respond to review comments

---
 .../lib/method_channel_url_launcher.dart      | 17 ++--
 .../lib/url_launcher_platform_interface.dart  | 24 ++---
 .../pubspec.yaml                              |  3 +
 .../method_channel_url_launcher_test.dart     | 96 +++++++++----------
 4 files changed, 73 insertions(+), 67 deletions(-)

diff --git a/packages/url_launcher/url_launcher_platform_interface/lib/method_channel_url_launcher.dart b/packages/url_launcher/url_launcher_platform_interface/lib/method_channel_url_launcher.dart
index 6e0ac187e91b..3fbd2ee01843 100644
--- a/packages/url_launcher/url_launcher_platform_interface/lib/method_channel_url_launcher.dart
+++ b/packages/url_launcher/url_launcher_platform_interface/lib/method_channel_url_launcher.dart
@@ -5,6 +5,7 @@
 import 'dart:async';
 
 import 'package:flutter/services.dart';
+import 'package:meta/meta.dart' show required;
 
 import 'url_launcher_platform_interface.dart';
 
@@ -27,14 +28,14 @@ class MethodChannelUrlLauncher extends UrlLauncherPlatform {
 
   @override
   Future<bool> launch(
-    String url,
-    bool useSafariVC,
-    bool useWebView,
-    bool enableJavaScript,
-    bool enableDomStorage,
-    bool universalLinksOnly,
-    Map<String, String> headers,
-  ) {
+    String url, {
+    @required bool useSafariVC,
+    @required bool useWebView,
+    @required bool enableJavaScript,
+    @required bool enableDomStorage,
+    @required bool universalLinksOnly,
+    @required Map<String, String> headers,
+  }) {
     return _channel.invokeMethod<bool>(
       'launch',
       <String, Object>{
diff --git a/packages/url_launcher/url_launcher_platform_interface/lib/url_launcher_platform_interface.dart b/packages/url_launcher/url_launcher_platform_interface/lib/url_launcher_platform_interface.dart
index 651a866e7403..8e1d090eef2b 100644
--- a/packages/url_launcher/url_launcher_platform_interface/lib/url_launcher_platform_interface.dart
+++ b/packages/url_launcher/url_launcher_platform_interface/lib/url_launcher_platform_interface.dart
@@ -4,6 +4,8 @@
 
 import 'dart:async';
 
+import 'package:meta/meta.dart' show required;
+
 import 'method_channel_url_launcher.dart';
 
 /// The interface that implementations of url_launcher must implement.
@@ -26,7 +28,7 @@ abstract class UrlLauncherPlatform {
 
   /// Returns `true` if this platform is able to launch [url].
   Future<bool> canLaunch(String url) {
-    throw new UnimplementedError('canLaunch() has not been implemented.');
+    throw UnimplementedError('canLaunch() has not been implemented.');
   }
 
   /// Returns `true` if the given [url] was successfully launched.
@@ -34,19 +36,19 @@ abstract class UrlLauncherPlatform {
   /// For documentation on the other arguments, see the `launch` documentation
   /// in `package:url_launcher/url_launcher.dart`.
   Future<bool> launch(
-    String url,
-    bool useSafariVC,
-    bool useWebView,
-    bool enableJavaScript,
-    bool enableDomStorage,
-    bool universalLinksOnly,
-    Map<String, String> headers,
-  ) {
-    throw new UnimplementedError('launch() has not been implemented.');
+    String url, {
+    @required bool useSafariVC,
+    @required bool useWebView,
+    @required bool enableJavaScript,
+    @required bool enableDomStorage,
+    @required bool universalLinksOnly,
+    @required Map<String, String> headers,
+  }) {
+    throw UnimplementedError('launch() has not been implemented.');
   }
 
   /// Closes the WebView, if one was opened earlier by [launch].
   Future<void> closeWebView() {
-    throw new UnimplementedError('closeWebView() has not been implemented.');
+    throw UnimplementedError('closeWebView() has not been implemented.');
   }
 }
diff --git a/packages/url_launcher/url_launcher_platform_interface/pubspec.yaml b/packages/url_launcher/url_launcher_platform_interface/pubspec.yaml
index ef59b68fbf44..99b260efe943 100644
--- a/packages/url_launcher/url_launcher_platform_interface/pubspec.yaml
+++ b/packages/url_launcher/url_launcher_platform_interface/pubspec.yaml
@@ -2,11 +2,14 @@ name: url_launcher_platform_interface
 description: A common platform interface for the url_launcher plugin.
 author: Flutter Team <flutter-dev@googlegroups.com>
 homepage: https://github.com/flutter/plugins/tree/master/packages/url_launcher/url_launcher_platform_interface
+# NOTE: We strongly prefer non-breaking changes, even at the expense of a
+# less-clean API. See https://flutter.dev/go/platform-interface-breaking-changes
 version: 1.0.0
 
 dependencies:
   flutter:
     sdk: flutter
+  meta: ^1.0.5
 
 dev_dependencies:
   flutter_test:
diff --git a/packages/url_launcher/url_launcher_platform_interface/test/method_channel_url_launcher_test.dart b/packages/url_launcher/url_launcher_platform_interface/test/method_channel_url_launcher_test.dart
index 6f7651b496cd..f409441903f3 100644
--- a/packages/url_launcher/url_launcher_platform_interface/test/method_channel_url_launcher_test.dart
+++ b/packages/url_launcher/url_launcher_platform_interface/test/method_channel_url_launcher_test.dart
@@ -44,12 +44,12 @@ void main() {
     test('launch', () async {
       await launcher.launch(
         'http://example.com/',
-        true,
-        false,
-        false,
-        false,
-        false,
-        const <String, String>{},
+        useSafariVC: true,
+        useWebView: false,
+        enableJavaScript: false,
+        enableDomStorage: false,
+        universalLinksOnly: false,
+        headers: const <String, String>{},
       );
       expect(
         log,
@@ -70,12 +70,12 @@ void main() {
     test('launch with headers', () async {
       await launcher.launch(
         'http://example.com/',
-        true,
-        false,
-        false,
-        false,
-        false,
-        const <String, String>{'key': 'value'},
+        useSafariVC: true,
+        useWebView: false,
+        enableJavaScript: false,
+        enableDomStorage: false,
+        universalLinksOnly: false,
+        headers: const <String, String>{'key': 'value'},
       );
       expect(
         log,
@@ -96,12 +96,12 @@ void main() {
     test('launch force SafariVC', () async {
       await launcher.launch(
         'http://example.com/',
-        true,
-        false,
-        false,
-        false,
-        false,
-        const <String, String>{},
+        useSafariVC: true,
+        useWebView: false,
+        enableJavaScript: false,
+        enableDomStorage: false,
+        universalLinksOnly: false,
+        headers: const <String, String>{},
       );
       expect(
         log,
@@ -122,12 +122,12 @@ void main() {
     test('launch universal links only', () async {
       await launcher.launch(
         'http://example.com/',
-        false,
-        false,
-        false,
-        false,
-        true,
-        const <String, String>{},
+        useSafariVC: false,
+        useWebView: false,
+        enableJavaScript: false,
+        enableDomStorage: false,
+        universalLinksOnly: true,
+        headers: const <String, String>{},
       );
       expect(
         log,
@@ -148,12 +148,12 @@ void main() {
     test('launch force WebView', () async {
       await launcher.launch(
         'http://example.com/',
-        true,
-        true,
-        false,
-        false,
-        false,
-        const <String, String>{},
+        useSafariVC: true,
+        useWebView: true,
+        enableJavaScript: false,
+        enableDomStorage: false,
+        universalLinksOnly: false,
+        headers: const <String, String>{},
       );
       expect(
         log,
@@ -174,12 +174,12 @@ void main() {
     test('launch force WebView enable javascript', () async {
       await launcher.launch(
         'http://example.com/',
-        true,
-        true,
-        true,
-        false,
-        false,
-        const <String, String>{},
+        useSafariVC: true,
+        useWebView: true,
+        enableJavaScript: true,
+        enableDomStorage: false,
+        universalLinksOnly: false,
+        headers: const <String, String>{},
       );
       expect(
         log,
@@ -200,12 +200,12 @@ void main() {
     test('launch force WebView enable DOM storage', () async {
       await launcher.launch(
         'http://example.com/',
-        true,
-        true,
-        false,
-        true,
-        false,
-        const <String, String>{},
+        useSafariVC: true,
+        useWebView: true,
+        enableJavaScript: false,
+        enableDomStorage: true,
+        universalLinksOnly: false,
+        headers: const <String, String>{},
       );
       expect(
         log,
@@ -226,12 +226,12 @@ void main() {
     test('launch force SafariVC to false', () async {
       await launcher.launch(
         'http://example.com/',
-        false,
-        false,
-        false,
-        false,
-        false,
-        const <String, String>{},
+        useSafariVC: false,
+        useWebView: false,
+        enableJavaScript: false,
+        enableDomStorage: false,
+        universalLinksOnly: false,
+        headers: const <String, String>{},
       );
       expect(
         log,