From 953e220652bd78c123cc179806b81cddb1d67ead Mon Sep 17 00:00:00 2001
From: Luis Thein <lthein@multamedio.de>
Date: Fri, 26 Jul 2019 13:09:54 +0200
Subject: [PATCH 01/20] Flutter implementation

  - Added userAgent field to WebView
  - Added userAgent getter to WebViewController
  - Updated CreationParams and WebViewSettings
  - Added MethodChannel for 'getUserAgent'
---
 .../lib/platform_interface.dart               | 25 +++++++++++++++--
 .../lib/src/webview_method_channel.dart       |  7 +++++
 .../webview_flutter/lib/webview_flutter.dart  | 28 ++++++++++++++++++-
 3 files changed, 56 insertions(+), 4 deletions(-)

diff --git a/packages/webview_flutter/lib/platform_interface.dart b/packages/webview_flutter/lib/platform_interface.dart
index bfb5b6255421..b708c3fba5b6 100644
--- a/packages/webview_flutter/lib/platform_interface.dart
+++ b/packages/webview_flutter/lib/platform_interface.dart
@@ -152,6 +152,11 @@ abstract class WebViewPlatformController {
     throw UnimplementedError(
         "WebView removeJavascriptChannels is not implemented on the current platform");
   }
+
+  Future<String> getUserAgent() {
+    throw UnimplementedError(
+        "WebView getUserAgent is not implemented on the current platform");
+  }
 }
 
 /// Settings for configuring a WebViewPlatform.
@@ -163,6 +168,7 @@ class WebSettings {
     this.javascriptMode,
     this.hasNavigationDelegate,
     this.debuggingEnabled,
+    this.userAgent,
   });
 
   /// The JavaScript execution mode to be used by the webview.
@@ -176,16 +182,24 @@ class WebSettings {
   /// See also: [WebView.debuggingEnabled].
   final bool debuggingEnabled;
 
+  /// The User Agent used for all following requests
+  ///
+  /// See also [WebView.userAgent]
+  final String userAgent;
+
   @override
   String toString() {
-    return 'WebSettings(javascriptMode: $javascriptMode, hasNavigationDelegate: $hasNavigationDelegate, debuggingEnabled: $debuggingEnabled)';
+    return 'WebSettings(javascriptMode: $javascriptMode, hasNavigationDelegate: $hasNavigationDelegate, debuggingEnabled: $debuggingEnabled, userAgent: $userAgent,)';
   }
 }
 
 /// Configuration to use when creating a new [WebViewPlatformController].
 class CreationParams {
   CreationParams(
-      {this.initialUrl, this.webSettings, this.javascriptChannelNames});
+      {this.initialUrl,
+      this.webSettings,
+      this.javascriptChannelNames,
+      this.userAgent});
 
   /// The initialUrl to load in the webview.
   ///
@@ -210,9 +224,14 @@ class CreationParams {
   // to PlatformWebView.
   final Set<String> javascriptChannelNames;
 
+  /// The User Agent used for all following requests
+  ///
+  /// When null, the default User Agent of the Android/iOS WebView is used
+  final String userAgent;
+
   @override
   String toString() {
-    return '$runtimeType(initialUrl: $initialUrl, settings: $webSettings, javascriptChannelNames: $javascriptChannelNames)';
+    return '$runtimeType(initialUrl: $initialUrl, settings: $webSettings, javascriptChannelNames: $javascriptChannelNames, UserAgent: $userAgent)';
   }
 }
 
diff --git a/packages/webview_flutter/lib/src/webview_method_channel.dart b/packages/webview_flutter/lib/src/webview_method_channel.dart
index ce9988743853..c5bdd1827236 100644
--- a/packages/webview_flutter/lib/src/webview_method_channel.dart
+++ b/packages/webview_flutter/lib/src/webview_method_channel.dart
@@ -103,6 +103,11 @@ class MethodChannelWebViewPlatform implements WebViewPlatformController {
         'removeJavascriptChannels', javascriptChannelNames.toList());
   }
 
+  @override
+  Future<String> getUserAgent() {
+    return _channel.invokeMethod('getUserAgent');
+  }
+
   /// Method channel mplementation for [WebViewPlatform.clearCookies].
   static Future<bool> clearCookies() {
     return _cookieManagerChannel
@@ -122,6 +127,7 @@ class MethodChannelWebViewPlatform implements WebViewPlatformController {
     _addIfNonNull('jsMode', settings.javascriptMode?.index);
     _addIfNonNull('hasNavigationDelegate', settings.hasNavigationDelegate);
     _addIfNonNull('debuggingEnabled', settings.debuggingEnabled);
+    _addIfNonNull('userAgent', settings.userAgent);
     return map;
   }
 
@@ -135,6 +141,7 @@ class MethodChannelWebViewPlatform implements WebViewPlatformController {
       'initialUrl': creationParams.initialUrl,
       'settings': _webSettingsToMap(creationParams.webSettings),
       'javascriptChannelNames': creationParams.javascriptChannelNames.toList(),
+      'userAgent': creationParams.userAgent,
     };
   }
 }
diff --git a/packages/webview_flutter/lib/webview_flutter.dart b/packages/webview_flutter/lib/webview_flutter.dart
index 3c0175e2f22b..47accb803ce5 100644
--- a/packages/webview_flutter/lib/webview_flutter.dart
+++ b/packages/webview_flutter/lib/webview_flutter.dart
@@ -121,6 +121,7 @@ class WebView extends StatefulWidget {
     this.gestureRecognizers,
     this.onPageFinished,
     this.debuggingEnabled = false,
+    this.userAgent,
   })  : assert(javascriptMode != null),
         super(key: key);
 
@@ -255,6 +256,18 @@ class WebView extends StatefulWidget {
   /// By default `debuggingEnabled` is false.
   final bool debuggingEnabled;
 
+  /// The User_Agent used for WebView requests.
+  ///
+  /// By default `userAgent` is null.
+  /// If the `userAgent` is null, the default User Agent from the Android / iOS WebView is used.
+  /// WebView User Agent for Android (https://developer.chrome.com/multidevice/user-agent)
+  ///
+  /// When the WebView is rebuild with a new User Agent, the page reloads and the request uses the new User Agent.
+  ///
+  /// When [WebViewController.goBack] is called after changing the User Agent, the old User Agent is used.
+  /// Only after reloading the Page you went back to,the request uses the new User Agent.
+  final String userAgent;
+
   @override
   State<StatefulWidget> createState() => _WebViewState();
 }
@@ -317,6 +330,7 @@ CreationParams _creationParamsfromWidget(WebView widget) {
     initialUrl: widget.initialUrl,
     webSettings: _webSettingsFromWidget(widget),
     javascriptChannelNames: _extractChannelNames(widget.javascriptChannels),
+    userAgent: widget.userAgent,
   );
 }
 
@@ -325,6 +339,7 @@ WebSettings _webSettingsFromWidget(WebView widget) {
     javascriptMode: widget.javascriptMode,
     hasNavigationDelegate: widget.navigationDelegate != null,
     debuggingEnabled: widget.debuggingEnabled,
+    userAgent: widget.userAgent,
   );
 }
 
@@ -337,9 +352,11 @@ WebSettings _clearUnchangedWebSettings(
   assert(newValue.javascriptMode != null);
   assert(newValue.hasNavigationDelegate != null);
   assert(newValue.debuggingEnabled != null);
+  assert(newValue.userAgent != null);
   JavascriptMode javascriptMode;
   bool hasNavigationDelegate;
   bool debuggingEnabled;
+  String userAgent;
   if (currentValue.javascriptMode != newValue.javascriptMode) {
     javascriptMode = newValue.javascriptMode;
   }
@@ -349,11 +366,15 @@ WebSettings _clearUnchangedWebSettings(
   if (currentValue.debuggingEnabled != newValue.debuggingEnabled) {
     debuggingEnabled = newValue.debuggingEnabled;
   }
+  if (currentValue.userAgent != newValue.userAgent) {
+    userAgent = newValue.userAgent;
+  }
 
   return WebSettings(
       javascriptMode: javascriptMode,
       hasNavigationDelegate: hasNavigationDelegate,
-      debuggingEnabled: debuggingEnabled);
+      debuggingEnabled: debuggingEnabled,
+      userAgent: userAgent);
 }
 
 Set<String> _extractChannelNames(Set<JavascriptChannel> channels) {
@@ -568,6 +589,11 @@ class WebViewController {
     // ignore: strong_mode_implicit_dynamic_method
     return _webViewPlatformController.evaluateJavascript(javascriptString);
   }
+
+  /// Returns the User Agent value that will be used for subsequent HTTP requests.
+  Future<String> getUserAgent() async {
+    return _webViewPlatformController.getUserAgent();
+  }
 }
 
 /// Manages cookies pertaining to all [WebView]s.

From 9478588f3fccda1f9eb0d7230b26e4854b8f115e Mon Sep 17 00:00:00 2001
From: Luis Thein <lthein@multamedio.de>
Date: Fri, 26 Jul 2019 13:19:01 +0200
Subject: [PATCH 02/20] Added Android implementation + updated example

  - added updateUserAgent Method
  - added getUserAgent Method
  - userAgent gets set in flutter example
---
 .../webviewflutter/FlutterWebView.java        | 20 +++++++++++++++++++
 .../webview_flutter/example/lib/main.dart     |  1 +
 2 files changed, 21 insertions(+)

diff --git a/packages/webview_flutter/android/src/main/java/io/flutter/plugins/webviewflutter/FlutterWebView.java b/packages/webview_flutter/android/src/main/java/io/flutter/plugins/webviewflutter/FlutterWebView.java
index 838987714d31..41bf9cf1affb 100644
--- a/packages/webview_flutter/android/src/main/java/io/flutter/plugins/webviewflutter/FlutterWebView.java
+++ b/packages/webview_flutter/android/src/main/java/io/flutter/plugins/webviewflutter/FlutterWebView.java
@@ -55,6 +55,11 @@ public class FlutterWebView implements PlatformView, MethodCallHandler {
       String url = (String) params.get("initialUrl");
       webView.loadUrl(url);
     }
+
+    if (params.containsKey("userAgent")) {
+      String userAgent = (String) params.get("userAgent");
+      updateUserAgent(userAgent);
+    }
   }
 
   @Override
@@ -121,6 +126,9 @@ public void onMethodCall(MethodCall methodCall, Result result) {
       case "clearCache":
         clearCache(result);
         break;
+      case "getUserAgent":
+        getUserAgent(methodCall, result);
+        break;
       default:
         result.notImplemented();
     }
@@ -232,6 +240,9 @@ private void applySettings(Map<String, Object> settings) {
 
           webView.setWebContentsDebuggingEnabled(debuggingEnabled);
           break;
+        case "userAgent":
+          updateUserAgent((String) settings.get(key));
+          break;
         default:
           throw new IllegalArgumentException("Unknown WebView setting: " + key);
       }
@@ -258,6 +269,15 @@ private void registerJavaScriptChannelNames(List<String> channelNames) {
     }
   }
 
+  private void getUserAgent(MethodCall methodCall, Result result) {
+    String userAgent = webView.getSettings().getUserAgentString();
+    result.success(userAgent);
+  }
+
+  private void updateUserAgent(String userAgent) {
+    webView.getSettings().setUserAgentString(userAgent);
+  }
+
   @Override
   public void dispose() {
     methodChannel.setMethodCallHandler(null);
diff --git a/packages/webview_flutter/example/lib/main.dart b/packages/webview_flutter/example/lib/main.dart
index 5f3e0f8ff4fa..17ac5c8fda09 100644
--- a/packages/webview_flutter/example/lib/main.dart
+++ b/packages/webview_flutter/example/lib/main.dart
@@ -53,6 +53,7 @@ class _WebViewExampleState extends State<WebViewExample> {
           onWebViewCreated: (WebViewController webViewController) {
             _controller.complete(webViewController);
           },
+          userAgent: 'Flutter_Custom_Agent',
           // TODO(iskakaushik): Remove this when collection literals makes it to stable.
           // ignore: prefer_collection_literals
           javascriptChannels: <JavascriptChannel>[

From 45e915dbc9af4cab11e4f470a4c3e3940b3f2fe5 Mon Sep 17 00:00:00 2001
From: Luis Thein <lthein@multamedio.de>
Date: Fri, 26 Jul 2019 13:23:05 +0200
Subject: [PATCH 03/20] iOS implementation

  - added onGetUserAgent Method
  - added updateUserAgent Method
  - updated applySettings Method
---
 .../ios/Classes/FlutterWebView.m              | 29 +++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/packages/webview_flutter/ios/Classes/FlutterWebView.m b/packages/webview_flutter/ios/Classes/FlutterWebView.m
index c56d5c7dbcc3..9f29215f928c 100644
--- a/packages/webview_flutter/ios/Classes/FlutterWebView.m
+++ b/packages/webview_flutter/ios/Classes/FlutterWebView.m
@@ -114,6 +114,8 @@ - (void)onMethodCall:(FlutterMethodCall*)call result:(FlutterResult)result {
     [self onRemoveJavaScriptChannels:call result:result];
   } else if ([[call method] isEqualToString:@"clearCache"]) {
     [self clearCache:result];
+  } else if ([[call method] isEqualToString:@"getUserAgent"]) {
+    [self onGetUserAgent:call result:result];
   } else {
     result(FlutterMethodNotImplemented);
   }
@@ -246,6 +248,9 @@ - (NSString*)applySettings:(NSDictionary<NSString*, id>*)settings {
       _navigationDelegate.hasDartNavigationDelegate = [hasDartNavigationDelegate boolValue];
     } else if ([key isEqualToString:@"debuggingEnabled"]) {
       // no-op debugging is always enabled on iOS.
+    } else if ([key isEqualToString:@"userAgent"]) {
+        NSString* userAgent = settings[key];
+        [self updateUserAgent:[userAgent isEqual:[NSNull null]] ? nil : userAgent];
     } else {
       [unknownKeys addObject:key];
     }
@@ -321,4 +326,28 @@ - (void)registerJavaScriptChannels:(NSSet*)channelNames
   }
 }
 
+- (void)onGetUserAgent:(FlutterMethodCall*)call result:(FlutterResult)result {
+    [_webView evaluateJavaScript:@"navigator.userAgent"
+               completionHandler:^(NSString* userAgent, NSError* error) {
+                   if (error) {
+                       result([FlutterError
+                               errorWithCode:@"userAgent_failed"
+                               message:@"Failed to get UserAgent"
+                               details:[NSString stringWithFormat:
+                                        @"webview_flutter: failed evaluating JavaScript: %@",
+                                        [error localizedDescription]]]);
+                   } else {
+                       result(userAgent);
+                   }
+               }];
+}
+
+- (void)updateUserAgent:(NSString*)userAgent {
+    if (@available(iOS 9.0, *)) {
+        [_webView setCustomUserAgent:userAgent];
+    } else {
+        NSLog(@"Updating UserAgent is not supported for Flutter WebViews prior to iOS 9.");
+    }
+}
+
 @end

From ae81a986d769090849503a5c25cdc515e6dd9ac5 Mon Sep 17 00:00:00 2001
From: Luis Thein <lthein@multamedio.de>
Date: Fri, 26 Jul 2019 13:59:30 +0200
Subject: [PATCH 04/20] Added Widget Test

---
 .../example/test_driver/webview.dart          | 43 +++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/packages/webview_flutter/example/test_driver/webview.dart b/packages/webview_flutter/example/test_driver/webview.dart
index 7a290a05bd5b..8bc68121fee2 100644
--- a/packages/webview_flutter/example/test_driver/webview.dart
+++ b/packages/webview_flutter/example/test_driver/webview.dart
@@ -132,6 +132,49 @@ void main() {
     await controller.evaluateJavascript('Echo.postMessage("hello");');
     expect(messagesReceived, equals(<String>['hello']));
   });
+
+  test('userAgent', () async {
+    final Completer<WebViewController> controllerCompleter1 =
+        Completer<WebViewController>();
+    await pumpWidget(
+      Directionality(
+        textDirection: TextDirection.ltr,
+        child: WebView(
+          key: GlobalKey(),
+          initialUrl: 'https://flutter.dev/',
+          javascriptMode: JavascriptMode.unrestricted,
+          userAgent: 'Custom_User_Agent1',
+          onWebViewCreated: (WebViewController controller) {
+            controllerCompleter1.complete(controller);
+          },
+        ),
+      ),
+    );
+    final WebViewController controller1 = await controllerCompleter1.future;
+    final String customUserAgent1 = await controller1.getUserAgent();
+    expect(customUserAgent1, 'Custom_User_Agent1');
+
+    // rebuilds a WebView with a different user agent.
+    final Completer<WebViewController> controllerCompleter2 =
+        Completer<WebViewController>();
+    await pumpWidget(
+      Directionality(
+        textDirection: TextDirection.ltr,
+        child: WebView(
+          key: GlobalKey(),
+          initialUrl: 'https://flutter.dev/',
+          javascriptMode: JavascriptMode.unrestricted,
+          userAgent: 'Custom_User_Agent2',
+          onWebViewCreated: (WebViewController controller) {
+            controllerCompleter2.complete(controller);
+          },
+        ),
+      ),
+    );
+    final WebViewController controller2 = await controllerCompleter2.future;
+    final String customUserAgent2 = await controller2.getUserAgent();
+    expect(customUserAgent2, 'Custom_User_Agent2');
+  });
 }
 
 Future<void> pumpWidget(Widget widget) {

From de27c9035408992e9454c3689f3b2468a63a8d0f Mon Sep 17 00:00:00 2001
From: Luis Thein <lthein@multamedio.de>
Date: Fri, 26 Jul 2019 15:48:40 +0200
Subject: [PATCH 05/20] Added unit tests for User Agent

  - added tests for get/set User Agent
  - allow currentValue.userAgent/newValue.userAgent to be null in _clearUnchangedWebSettings
---
 .../webview_flutter/lib/webview_flutter.dart  |  3 +-
 .../test/webview_flutter_test.dart            | 46 ++++++++++++++++++-
 2 files changed, 45 insertions(+), 4 deletions(-)

diff --git a/packages/webview_flutter/lib/webview_flutter.dart b/packages/webview_flutter/lib/webview_flutter.dart
index 47accb803ce5..42cc15d0eea1 100644
--- a/packages/webview_flutter/lib/webview_flutter.dart
+++ b/packages/webview_flutter/lib/webview_flutter.dart
@@ -343,7 +343,7 @@ WebSettings _webSettingsFromWidget(WebView widget) {
   );
 }
 
-// This method assumes that no fields in `currentValue` are null.
+// This method assumes that no fields, except userAgent (see WebView.userAgent), in `currentValue` are null.
 WebSettings _clearUnchangedWebSettings(
     WebSettings currentValue, WebSettings newValue) {
   assert(currentValue.javascriptMode != null);
@@ -352,7 +352,6 @@ WebSettings _clearUnchangedWebSettings(
   assert(newValue.javascriptMode != null);
   assert(newValue.hasNavigationDelegate != null);
   assert(newValue.debuggingEnabled != null);
-  assert(newValue.userAgent != null);
   JavascriptMode javascriptMode;
   bool hasNavigationDelegate;
   bool debuggingEnabled;
diff --git a/packages/webview_flutter/test/webview_flutter_test.dart b/packages/webview_flutter/test/webview_flutter_test.dart
index d451a86b19c8..a6d96a19202a 100644
--- a/packages/webview_flutter/test/webview_flutter_test.dart
+++ b/packages/webview_flutter/test/webview_flutter_test.dart
@@ -807,6 +807,41 @@ void main() {
       expect(platform.lastRequestHeaders, headers);
     });
   });
+  testWidgets('Set UserAgent', (WidgetTester tester) async {
+    await tester.pumpWidget(const WebView(
+      initialUrl: 'https://youtube.com',
+      javascriptMode: JavascriptMode.unrestricted,
+    ));
+
+    final FakePlatformWebView platformWebView =
+        fakePlatformViewsController.lastCreatedView;
+
+    expect(platformWebView.userAgent, isNull);
+
+    await tester.pumpWidget(const WebView(
+      initialUrl: 'https://youtube.com',
+      javascriptMode: JavascriptMode.unrestricted,
+      userAgent: 'UA',
+    ));
+
+    expect(platformWebView.userAgent, 'UA');
+  });
+
+  testWidgets('Get UserAgent', (WidgetTester tester) async {
+    WebViewController controller;
+    await tester.pumpWidget(
+      WebView(
+        initialUrl: 'https://youtube.com',
+        javascriptMode: JavascriptMode.unrestricted,
+        userAgent: 'UA',
+        onWebViewCreated: (WebViewController webViewController) {
+          controller = webViewController;
+        },
+      ),
+    );
+    expect(controller, isNotNull);
+    expect(await controller.getUserAgent(), 'UA');
+  });
 }
 
 class FakePlatformWebView {
@@ -826,7 +861,7 @@ class FakePlatformWebView {
     hasNavigationDelegate =
         params['settings']['hasNavigationDelegate'] ?? false;
     debuggingEnabled = params['settings']['debuggingEnabled'];
-
+    userAgent = params['settings']['userAgent'];
     channel = MethodChannel(
         'plugins.flutter.io/webview_$id', const StandardMethodCodec());
     channel.setMockMethodCallHandler(onMethodCall);
@@ -845,6 +880,7 @@ class FakePlatformWebView {
 
   bool hasNavigationDelegate;
   bool debuggingEnabled;
+  String userAgent;
 
   Future<dynamic> onMethodCall(MethodCall call) {
     switch (call.method) {
@@ -862,6 +898,9 @@ class FakePlatformWebView {
         if (call.arguments['debuggingEnabled'] != null) {
           debuggingEnabled = call.arguments['debuggingEnabled'];
         }
+        if (call.arguments['userAgent'] != null) {
+          userAgent = call.arguments['userAgent'];
+        }
         break;
       case 'canGoBack':
         return Future<bool>.sync(() => currentPosition > 0);
@@ -898,6 +937,8 @@ class FakePlatformWebView {
       case 'clearCache':
         hasCache = false;
         return Future<void>.sync(() {});
+      case 'getUserAgent':
+        return Future<String>.value(userAgent);
     }
     return Future<void>.sync(() {});
   }
@@ -1092,7 +1133,8 @@ class MatchesWebSettings extends Matcher {
     return _webSettings.javascriptMode == webSettings.javascriptMode &&
         _webSettings.hasNavigationDelegate ==
             webSettings.hasNavigationDelegate &&
-        _webSettings.debuggingEnabled == webSettings.debuggingEnabled;
+        _webSettings.debuggingEnabled == webSettings.debuggingEnabled &&
+        _webSettings.userAgent == webSettings.userAgent;
   }
 }
 

From cbcc808e42c6855a9c35020835bd61bbec4e74b5 Mon Sep 17 00:00:00 2001
From: Luis Thein <luis.thein@gmx.de>
Date: Sat, 27 Jul 2019 14:19:46 +0200
Subject: [PATCH 06/20] Updated CHANGELOG.md

---
 packages/webview_flutter/CHANGELOG.md | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/packages/webview_flutter/CHANGELOG.md b/packages/webview_flutter/CHANGELOG.md
index 7904efa1998a..816ac119cfd4 100644
--- a/packages/webview_flutter/CHANGELOG.md
+++ b/packages/webview_flutter/CHANGELOG.md
@@ -1,3 +1,8 @@
+## 0.3.11
+
+* Add an optional `userAgent` property to set a custom User Agent.
+  Add `getUserAgent` to WebViewController. 
+
 ## 0.3.10+3
 
 * Don't log an unknown setting key error for 'debuggingEnabled' on iOS.

From d54e0bcc8d556d07399aa023770c61c201fadc51 Mon Sep 17 00:00:00 2001
From: Luis Thein <luis.thein@gmx.de>
Date: Sat, 27 Jul 2019 15:47:51 +0200
Subject: [PATCH 07/20] Fixed format error in FlutterwebView.m

---
 .../ios/Classes/FlutterWebView.m              | 27 ++++++++++---------
 1 file changed, 14 insertions(+), 13 deletions(-)

diff --git a/packages/webview_flutter/ios/Classes/FlutterWebView.m b/packages/webview_flutter/ios/Classes/FlutterWebView.m
index 9f29215f928c..a0ae992b3941 100644
--- a/packages/webview_flutter/ios/Classes/FlutterWebView.m
+++ b/packages/webview_flutter/ios/Classes/FlutterWebView.m
@@ -327,19 +327,20 @@ - (void)registerJavaScriptChannels:(NSSet*)channelNames
 }
 
 - (void)onGetUserAgent:(FlutterMethodCall*)call result:(FlutterResult)result {
-    [_webView evaluateJavaScript:@"navigator.userAgent"
-               completionHandler:^(NSString* userAgent, NSError* error) {
-                   if (error) {
-                       result([FlutterError
-                               errorWithCode:@"userAgent_failed"
-                               message:@"Failed to get UserAgent"
-                               details:[NSString stringWithFormat:
-                                        @"webview_flutter: failed evaluating JavaScript: %@",
-                                        [error localizedDescription]]]);
-                   } else {
-                       result(userAgent);
-                   }
-               }];
+  [_webView
+      evaluateJavaScript:@"navigator.userAgent"
+       completionHandler:^(NSString* userAgent, NSError* error) {
+         if (error) {
+           result([FlutterError
+               errorWithCode:@"userAgent_failed"
+                     message:@"Failed to get UserAgent"
+                     details:[NSString stringWithFormat:
+                                           @"webview_flutter: failed evaluating JavaScript: %@",
+                                           [error localizedDescription]]]);
+         } else {
+           result(userAgent);
+         }
+       }];
 }
 
 - (void)updateUserAgent:(NSString*)userAgent {

From 86d44caef2db5e6b3b9fb29a0c375d43ba6b669e Mon Sep 17 00:00:00 2001
From: Luis Thein <luis.thein@gmx.de>
Date: Sat, 27 Jul 2019 18:49:00 +0200
Subject: [PATCH 08/20] Fixed another format error

---
 .../webview_flutter/ios/Classes/FlutterWebView.m   | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/packages/webview_flutter/ios/Classes/FlutterWebView.m b/packages/webview_flutter/ios/Classes/FlutterWebView.m
index a0ae992b3941..9b9b6edf1310 100644
--- a/packages/webview_flutter/ios/Classes/FlutterWebView.m
+++ b/packages/webview_flutter/ios/Classes/FlutterWebView.m
@@ -249,8 +249,8 @@ - (NSString*)applySettings:(NSDictionary<NSString*, id>*)settings {
     } else if ([key isEqualToString:@"debuggingEnabled"]) {
       // no-op debugging is always enabled on iOS.
     } else if ([key isEqualToString:@"userAgent"]) {
-        NSString* userAgent = settings[key];
-        [self updateUserAgent:[userAgent isEqual:[NSNull null]] ? nil : userAgent];
+      NSString* userAgent = settings[key];
+      [self updateUserAgent:[userAgent isEqual:[NSNull null]] ? nil : userAgent];
     } else {
       [unknownKeys addObject:key];
     }
@@ -344,11 +344,11 @@ - (void)onGetUserAgent:(FlutterMethodCall*)call result:(FlutterResult)result {
 }
 
 - (void)updateUserAgent:(NSString*)userAgent {
-    if (@available(iOS 9.0, *)) {
-        [_webView setCustomUserAgent:userAgent];
-    } else {
-        NSLog(@"Updating UserAgent is not supported for Flutter WebViews prior to iOS 9.");
-    }
+  if (@available(iOS 9.0, *)) {
+    [_webView setCustomUserAgent:userAgent];
+  } else {
+    NSLog(@"Updating UserAgent is not supported for Flutter WebViews prior to iOS 9.");
+  }
 }
 
 @end

From 7b26a413c58b18323cebf6cee4538ae338e0e170 Mon Sep 17 00:00:00 2001
From: Luis Thein <lthein@multamedio.de>
Date: Mon, 5 Aug 2019 10:35:16 +0200
Subject: [PATCH 09/20] Changed files according to pull request review

  - Updated Dartdoc comments
  - Changed tests to reuse one globalkey
  - Added test for rebuilding the webView with no user agent after setting the user agent
---
 .../example/test_driver/webview.dart          | 65 ++++++++++++++++---
 .../lib/platform_interface.dart               |  7 +-
 .../lib/src/webview_method_channel.dart       |  2 +-
 .../webview_flutter/lib/webview_flutter.dart  | 16 +++--
 4 files changed, 69 insertions(+), 21 deletions(-)

diff --git a/packages/webview_flutter/example/test_driver/webview.dart b/packages/webview_flutter/example/test_driver/webview.dart
index 8bc68121fee2..679efe659925 100644
--- a/packages/webview_flutter/example/test_driver/webview.dart
+++ b/packages/webview_flutter/example/test_driver/webview.dart
@@ -133,14 +133,15 @@ void main() {
     expect(messagesReceived, equals(<String>['hello']));
   });
 
-  test('userAgent', () async {
+  test('set custom userAgent', () async {
     final Completer<WebViewController> controllerCompleter1 =
         Completer<WebViewController>();
+    final GlobalKey _globalKey = GlobalKey();
     await pumpWidget(
       Directionality(
         textDirection: TextDirection.ltr,
         child: WebView(
-          key: GlobalKey(),
+          key: _globalKey,
           initialUrl: 'https://flutter.dev/',
           javascriptMode: JavascriptMode.unrestricted,
           userAgent: 'Custom_User_Agent1',
@@ -153,27 +154,71 @@ void main() {
     final WebViewController controller1 = await controllerCompleter1.future;
     final String customUserAgent1 = await controller1.getUserAgent();
     expect(customUserAgent1, 'Custom_User_Agent1');
+    // rebuild the WebView with a different user agent.
+    await pumpWidget(
+      Directionality(
+        textDirection: TextDirection.ltr,
+        child: WebView(
+          key: _globalKey,
+          initialUrl: 'https://flutter.dev/',
+          javascriptMode: JavascriptMode.unrestricted,
+          userAgent: 'Custom_User_Agent2',
+        ),
+      ),
+    );
 
-    // rebuilds a WebView with a different user agent.
-    final Completer<WebViewController> controllerCompleter2 =
+    final String customUserAgent2 = await controller1.getUserAgent();
+    expect(customUserAgent2, 'Custom_User_Agent2');
+  });
+
+  test('use default platform userAgent after webView is rebuilt', () async {
+    final Completer<WebViewController> controllerCompleter =
         Completer<WebViewController>();
+    final GlobalKey _globalKey = GlobalKey();
+    // Build the webView with no user agent to get the default platform user agent.
     await pumpWidget(
       Directionality(
         textDirection: TextDirection.ltr,
         child: WebView(
-          key: GlobalKey(),
+          key: _globalKey,
           initialUrl: 'https://flutter.dev/',
           javascriptMode: JavascriptMode.unrestricted,
-          userAgent: 'Custom_User_Agent2',
           onWebViewCreated: (WebViewController controller) {
-            controllerCompleter2.complete(controller);
+            controllerCompleter.complete(controller);
           },
         ),
       ),
     );
-    final WebViewController controller2 = await controllerCompleter2.future;
-    final String customUserAgent2 = await controller2.getUserAgent();
-    expect(customUserAgent2, 'Custom_User_Agent2');
+    final WebViewController controller = await controllerCompleter.future;
+    final String defaultPlatformUserAgent = await controller.getUserAgent();
+    // rebuild the WebView with a custom user agent.
+    await pumpWidget(
+      Directionality(
+        textDirection: TextDirection.ltr,
+        child: WebView(
+          key: _globalKey,
+          initialUrl: 'https://flutter.dev/',
+          javascriptMode: JavascriptMode.unrestricted,
+          userAgent: 'Custom_User_Agent',
+        ),
+      ),
+    );
+    final String customUserAgent = await controller.getUserAgent();
+    expect(customUserAgent, 'Custom_User_Agent');
+    // rebuilds the WebView with no user agent.
+    await pumpWidget(
+      Directionality(
+        textDirection: TextDirection.ltr,
+        child: WebView(
+          key: _globalKey,
+          initialUrl: 'https://flutter.dev/',
+          javascriptMode: JavascriptMode.unrestricted,
+        ),
+      ),
+    );
+
+    final String customUserAgent2 = await controller.getUserAgent();
+    expect(customUserAgent2, defaultPlatformUserAgent);
   });
 }
 
diff --git a/packages/webview_flutter/lib/platform_interface.dart b/packages/webview_flutter/lib/platform_interface.dart
index b708c3fba5b6..2f8fb62ad930 100644
--- a/packages/webview_flutter/lib/platform_interface.dart
+++ b/packages/webview_flutter/lib/platform_interface.dart
@@ -153,6 +153,7 @@ abstract class WebViewPlatformController {
         "WebView removeJavascriptChannels is not implemented on the current platform");
   }
 
+  /// Returns the current user agent used for the HTTP User-Agent: request header.
   Future<String> getUserAgent() {
     throw UnimplementedError(
         "WebView getUserAgent is not implemented on the current platform");
@@ -182,7 +183,7 @@ class WebSettings {
   /// See also: [WebView.debuggingEnabled].
   final bool debuggingEnabled;
 
-  /// The User Agent used for all following requests
+  /// The value used for the HTTP User-Agent: request header.
   ///
   /// See also [WebView.userAgent]
   final String userAgent;
@@ -224,9 +225,9 @@ class CreationParams {
   // to PlatformWebView.
   final Set<String> javascriptChannelNames;
 
-  /// The User Agent used for all following requests
+  /// The value used for the HTTP User-Agent: request header.
   ///
-  /// When null, the default User Agent of the Android/iOS WebView is used
+  /// When null the platform's webview default is used for the User-Agent header.
   final String userAgent;
 
   @override
diff --git a/packages/webview_flutter/lib/src/webview_method_channel.dart b/packages/webview_flutter/lib/src/webview_method_channel.dart
index c5bdd1827236..56ec71994f9e 100644
--- a/packages/webview_flutter/lib/src/webview_method_channel.dart
+++ b/packages/webview_flutter/lib/src/webview_method_channel.dart
@@ -127,7 +127,7 @@ class MethodChannelWebViewPlatform implements WebViewPlatformController {
     _addIfNonNull('jsMode', settings.javascriptMode?.index);
     _addIfNonNull('hasNavigationDelegate', settings.hasNavigationDelegate);
     _addIfNonNull('debuggingEnabled', settings.debuggingEnabled);
-    _addIfNonNull('userAgent', settings.userAgent);
+    map['userAgent'] = settings.userAgent;
     return map;
   }
 
diff --git a/packages/webview_flutter/lib/webview_flutter.dart b/packages/webview_flutter/lib/webview_flutter.dart
index 42cc15d0eea1..58132315f06e 100644
--- a/packages/webview_flutter/lib/webview_flutter.dart
+++ b/packages/webview_flutter/lib/webview_flutter.dart
@@ -256,16 +256,18 @@ class WebView extends StatefulWidget {
   /// By default `debuggingEnabled` is false.
   final bool debuggingEnabled;
 
-  /// The User_Agent used for WebView requests.
+  /// The value used for the HTTP User-Agent: request header.
   ///
-  /// By default `userAgent` is null.
-  /// If the `userAgent` is null, the default User Agent from the Android / iOS WebView is used.
-  /// WebView User Agent for Android (https://developer.chrome.com/multidevice/user-agent)
+  /// Updating UserAgent is not supported for Flutter WebViews prior to iOS 9.
+  ///
+  /// When null the platform's webview default is used for the User-Agent header.
+  /// Webview user agent for Android (https://developer.chrome.com/multidevice/user-agent)
   ///
-  /// When the WebView is rebuild with a new User Agent, the page reloads and the request uses the new User Agent.
+  /// When the [WebView] is rebuilt with a new user agent, the page reloads and the request uses the new User Agent.
   ///
-  /// When [WebViewController.goBack] is called after changing the User Agent, the old User Agent is used.
-  /// Only after reloading the Page you went back to,the request uses the new User Agent.
+  /// When [WebViewController.goBack] is called after changing userAgent the previous userAgent value is used until the page is reloaded.
+  ///
+  /// By default `userAgent` is null.
   final String userAgent;
 
   @override

From 7fed0321b657b3ff4414002bfb2d471a12f9f62b Mon Sep 17 00:00:00 2001
From: Luis Thein <lthein@multamedio.de>
Date: Mon, 5 Aug 2019 11:04:23 +0200
Subject: [PATCH 10/20] Minor changes

  - Added comment to _webSettingsToMap regarding nullability of user agent
  - Changed handling of null user agent in FakePlatformWebView according to changes in WebviewMethodChannel
---
 packages/webview_flutter/lib/src/webview_method_channel.dart | 1 +
 packages/webview_flutter/test/webview_flutter_test.dart      | 4 +---
 2 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/packages/webview_flutter/lib/src/webview_method_channel.dart b/packages/webview_flutter/lib/src/webview_method_channel.dart
index 56ec71994f9e..33e48ae9029f 100644
--- a/packages/webview_flutter/lib/src/webview_method_channel.dart
+++ b/packages/webview_flutter/lib/src/webview_method_channel.dart
@@ -127,6 +127,7 @@ class MethodChannelWebViewPlatform implements WebViewPlatformController {
     _addIfNonNull('jsMode', settings.javascriptMode?.index);
     _addIfNonNull('hasNavigationDelegate', settings.hasNavigationDelegate);
     _addIfNonNull('debuggingEnabled', settings.debuggingEnabled);
+    // always add the user agent, as null is a valid value for the user agent. See [WebView.userAgent]
     map['userAgent'] = settings.userAgent;
     return map;
   }
diff --git a/packages/webview_flutter/test/webview_flutter_test.dart b/packages/webview_flutter/test/webview_flutter_test.dart
index a6d96a19202a..e6f7b9933877 100644
--- a/packages/webview_flutter/test/webview_flutter_test.dart
+++ b/packages/webview_flutter/test/webview_flutter_test.dart
@@ -898,9 +898,7 @@ class FakePlatformWebView {
         if (call.arguments['debuggingEnabled'] != null) {
           debuggingEnabled = call.arguments['debuggingEnabled'];
         }
-        if (call.arguments['userAgent'] != null) {
-          userAgent = call.arguments['userAgent'];
-        }
+        userAgent = call.arguments['userAgent'];
         break;
       case 'canGoBack':
         return Future<bool>.sync(() => currentPosition > 0);

From c5cc6a711a943ea149c536c8591f959e90f805cf Mon Sep 17 00:00:00 2001
From: Luis Thein <lthein@multamedio.de>
Date: Mon, 5 Aug 2019 11:15:29 +0200
Subject: [PATCH 11/20] Updated dartdoc for WebView.userAgent

---
 packages/webview_flutter/lib/webview_flutter.dart | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/packages/webview_flutter/lib/webview_flutter.dart b/packages/webview_flutter/lib/webview_flutter.dart
index 58132315f06e..e0a3652a90c3 100644
--- a/packages/webview_flutter/lib/webview_flutter.dart
+++ b/packages/webview_flutter/lib/webview_flutter.dart
@@ -258,8 +258,6 @@ class WebView extends StatefulWidget {
 
   /// The value used for the HTTP User-Agent: request header.
   ///
-  /// Updating UserAgent is not supported for Flutter WebViews prior to iOS 9.
-  ///
   /// When null the platform's webview default is used for the User-Agent header.
   /// Webview user agent for Android (https://developer.chrome.com/multidevice/user-agent)
   ///
@@ -267,6 +265,8 @@ class WebView extends StatefulWidget {
   ///
   /// When [WebViewController.goBack] is called after changing userAgent the previous userAgent value is used until the page is reloaded.
   ///
+  /// Updating UserAgent is not supported for Flutter WebViews prior to iOS 9.
+  ///
   /// By default `userAgent` is null.
   final String userAgent;
 

From 79761515b33c3e96234e7b0555651c74f971adee Mon Sep 17 00:00:00 2001
From: Amir Hardon <amirha@google.com>
Date: Wed, 14 Aug 2019 11:11:43 -0700
Subject: [PATCH 12/20] Use a WebSetting<T> type to allow representing absence
 of a null value.

---
 .../lib/platform_interface.dart               | 64 +++++++++++++++++--
 .../lib/src/webview_method_channel.dart       | 11 +++-
 .../webview_flutter/lib/webview_flutter.dart  |  9 ++-
 .../test/webview_flutter_test.dart            |  1 +
 4 files changed, 74 insertions(+), 11 deletions(-)

diff --git a/packages/webview_flutter/lib/platform_interface.dart b/packages/webview_flutter/lib/platform_interface.dart
index 8b9ea5ceabd8..ac1330ec524b 100644
--- a/packages/webview_flutter/lib/platform_interface.dart
+++ b/packages/webview_flutter/lib/platform_interface.dart
@@ -160,17 +160,66 @@ abstract class WebViewPlatformController {
   }
 }
 
+/// A single setting for configuring a WebViewPlatform which may be absent.
+class WebSetting<T> {
+  /// Constructs an absent setting instance.
+  ///
+  /// The [isPresent] field for the instance will be false.
+  ///
+  /// Accessing [value] for an absent instance will throw.
+  WebSetting.absent()
+      : _value = null,
+        isPresent = false;
+
+  /// Constructs a setting of the given `value`.
+  ///
+  /// The [isPresent] field for the instance will be true.
+  WebSetting.of(T value)
+      : _value = value,
+        isPresent = true;
+
+  final T _value;
+
+  /// The setting's value.
+  ///
+  /// Throws if [WebSetting.isPresent] is false.
+  T get value {
+    if (!isPresent) {
+      throw StateError('Cannot access a value of an absent WebSetting');
+    }
+    assert(isPresent);
+    return _value;
+  }
+
+  /// True when this web setting instance contains a value.
+  ///
+  /// When false the [WebSetting.value] getter throws.
+  final bool isPresent;
+
+  @override
+  bool operator ==(Object other) {
+    if (other.runtimeType != runtimeType) return false;
+    final WebSetting<T> typedOther = other;
+    return typedOther.isPresent == isPresent && typedOther._value == _value;
+  }
+
+  @override
+  int get hashCode => hashValues(_value, isPresent);
+}
+
 /// Settings for configuring a WebViewPlatform.
 ///
 /// Initial settings are passed as part of [CreationParams], settings updates are sent with
 /// [WebViewPlatform#updateSettings].
+///
+/// The `userAgent` parameter must not be null.
 class WebSettings {
   WebSettings({
     this.javascriptMode,
     this.hasNavigationDelegate,
     this.debuggingEnabled,
-    this.userAgent,
-  });
+    @required this.userAgent,
+  }) : assert(userAgent != null);
 
   /// The JavaScript execution mode to be used by the webview.
   final JavascriptMode javascriptMode;
@@ -183,10 +232,15 @@ class WebSettings {
   /// See also: [WebView.debuggingEnabled].
   final bool debuggingEnabled;
 
-  /// The value used for the HTTP User-Agent: request header.
+  /// The value used for the HTTP `User-Agent:` request header.
   ///
-  /// See also [WebView.userAgent]
-  final String userAgent;
+  /// If [userAgent.value] is null the platform's default user agent should be used.
+  ///
+  /// An absent value ([userAgent.isPresent] is false) represents no change to this setting from the
+  /// last time it was set.
+  ///
+  /// See also [WebView.userAgent].
+  final WebSetting<String> userAgent;
 
   @override
   String toString() {
diff --git a/packages/webview_flutter/lib/src/webview_method_channel.dart b/packages/webview_flutter/lib/src/webview_method_channel.dart
index 1b8fb5de26b4..eff948625480 100644
--- a/packages/webview_flutter/lib/src/webview_method_channel.dart
+++ b/packages/webview_flutter/lib/src/webview_method_channel.dart
@@ -108,7 +108,6 @@ class MethodChannelWebViewPlatform implements WebViewPlatformController {
     return _channel.invokeMethod('getUserAgent');
   }
 
-  /// Method channel mplementation for [WebViewPlatform.clearCookies].
   /// Method channel implementation for [WebViewPlatform.clearCookies].
   static Future<bool> clearCookies() {
     return _cookieManagerChannel
@@ -125,11 +124,17 @@ class MethodChannelWebViewPlatform implements WebViewPlatformController {
       map[key] = value;
     }
 
+    void _addSettingIfPresent<T>(String key, WebSetting<T> setting) {
+      if (!setting.isPresent) {
+        return;
+      }
+      map[key] = setting.value;
+    }
+
     _addIfNonNull('jsMode', settings.javascriptMode?.index);
     _addIfNonNull('hasNavigationDelegate', settings.hasNavigationDelegate);
     _addIfNonNull('debuggingEnabled', settings.debuggingEnabled);
-    // always add the user agent, as null is a valid value for the user agent. See [WebView.userAgent]
-    map['userAgent'] = settings.userAgent;
+    _addSettingIfPresent('userAgent', settings.userAgent);
     return map;
   }
 
diff --git a/packages/webview_flutter/lib/webview_flutter.dart b/packages/webview_flutter/lib/webview_flutter.dart
index 486a9b40b9ba..b257dc9915f2 100644
--- a/packages/webview_flutter/lib/webview_flutter.dart
+++ b/packages/webview_flutter/lib/webview_flutter.dart
@@ -372,23 +372,26 @@ WebSettings _webSettingsFromWidget(WebView widget) {
     javascriptMode: widget.javascriptMode,
     hasNavigationDelegate: widget.navigationDelegate != null,
     debuggingEnabled: widget.debuggingEnabled,
-    userAgent: widget.userAgent,
+    userAgent: WebSetting<String>.of(widget.userAgent),
   );
 }
 
-// This method assumes that no fields, except userAgent (see WebView.userAgent), in `currentValue` are null.
+// This method assumes that no fields in `currentValue` are null.
 WebSettings _clearUnchangedWebSettings(
     WebSettings currentValue, WebSettings newValue) {
   assert(currentValue.javascriptMode != null);
   assert(currentValue.hasNavigationDelegate != null);
   assert(currentValue.debuggingEnabled != null);
+  assert(currentValue.userAgent.isPresent);
   assert(newValue.javascriptMode != null);
   assert(newValue.hasNavigationDelegate != null);
   assert(newValue.debuggingEnabled != null);
+  assert(newValue.userAgent.isPresent);
+
   JavascriptMode javascriptMode;
   bool hasNavigationDelegate;
   bool debuggingEnabled;
-  String userAgent;
+  WebSetting<String> userAgent = WebSetting<String>.absent();
   if (currentValue.javascriptMode != newValue.javascriptMode) {
     javascriptMode = newValue.javascriptMode;
   }
diff --git a/packages/webview_flutter/test/webview_flutter_test.dart b/packages/webview_flutter/test/webview_flutter_test.dart
index e6f7b9933877..069aede4de45 100644
--- a/packages/webview_flutter/test/webview_flutter_test.dart
+++ b/packages/webview_flutter/test/webview_flutter_test.dart
@@ -776,6 +776,7 @@ void main() {
               javascriptMode: JavascriptMode.disabled,
               hasNavigationDelegate: false,
               debuggingEnabled: false,
+              userAgent: WebSetting<String>.of(null),
             ),
             // TODO(iskakaushik): Remove this when collection literals makes it to stable.
             // ignore: prefer_collection_literals

From 4c0d2f30258d6eacc0900756209c4a3f9f38a13c Mon Sep 17 00:00:00 2001
From: Amir Hardon <amirha@google.com>
Date: Wed, 14 Aug 2019 12:25:06 -0700
Subject: [PATCH 13/20] review fixes

---
 .../flutter/plugins/webviewflutter/FlutterWebView.java   | 9 ++++-----
 packages/webview_flutter/example/lib/main.dart           | 1 -
 packages/webview_flutter/lib/platform_interface.dart     | 2 +-
 packages/webview_flutter/lib/webview_flutter.dart        | 8 ++++----
 4 files changed, 9 insertions(+), 11 deletions(-)

diff --git a/packages/webview_flutter/android/src/main/java/io/flutter/plugins/webviewflutter/FlutterWebView.java b/packages/webview_flutter/android/src/main/java/io/flutter/plugins/webviewflutter/FlutterWebView.java
index 27ba2db33cce..4dfcda0f4e7b 100644
--- a/packages/webview_flutter/android/src/main/java/io/flutter/plugins/webviewflutter/FlutterWebView.java
+++ b/packages/webview_flutter/android/src/main/java/io/flutter/plugins/webviewflutter/FlutterWebView.java
@@ -60,15 +60,14 @@ public class FlutterWebView implements PlatformView, MethodCallHandler {
     }
 
     updateAutoMediaPlaybackPolicy((Integer) params.get("autoMediaPlaybackPolicy"));
-    if (params.containsKey("initialUrl")) {
-      String url = (String) params.get("initialUrl");
-      webView.loadUrl(url);
-    }
-
     if (params.containsKey("userAgent")) {
       String userAgent = (String) params.get("userAgent");
       updateUserAgent(userAgent);
     }
+    if (params.containsKey("initialUrl")) {
+      String url = (String) params.get("initialUrl");
+      webView.loadUrl(url);
+    }
   }
 
   @Override
diff --git a/packages/webview_flutter/example/lib/main.dart b/packages/webview_flutter/example/lib/main.dart
index 17ac5c8fda09..5f3e0f8ff4fa 100644
--- a/packages/webview_flutter/example/lib/main.dart
+++ b/packages/webview_flutter/example/lib/main.dart
@@ -53,7 +53,6 @@ class _WebViewExampleState extends State<WebViewExample> {
           onWebViewCreated: (WebViewController webViewController) {
             _controller.complete(webViewController);
           },
-          userAgent: 'Flutter_Custom_Agent',
           // TODO(iskakaushik): Remove this when collection literals makes it to stable.
           // ignore: prefer_collection_literals
           javascriptChannels: <JavascriptChannel>[
diff --git a/packages/webview_flutter/lib/platform_interface.dart b/packages/webview_flutter/lib/platform_interface.dart
index ac1330ec524b..6b6c518a0689 100644
--- a/packages/webview_flutter/lib/platform_interface.dart
+++ b/packages/webview_flutter/lib/platform_interface.dart
@@ -153,7 +153,7 @@ abstract class WebViewPlatformController {
         "WebView removeJavascriptChannels is not implemented on the current platform");
   }
 
-  /// Returns the current user agent used for the HTTP User-Agent: request header.
+  /// Returns the value used for the HTTP User-Agent: request header in subsequent HTTP requests.
   Future<String> getUserAgent() {
     throw UnimplementedError(
         "WebView getUserAgent is not implemented on the current platform");
diff --git a/packages/webview_flutter/lib/webview_flutter.dart b/packages/webview_flutter/lib/webview_flutter.dart
index b257dc9915f2..e0345e0c5c5a 100644
--- a/packages/webview_flutter/lib/webview_flutter.dart
+++ b/packages/webview_flutter/lib/webview_flutter.dart
@@ -281,13 +281,13 @@ class WebView extends StatefulWidget {
   /// The value used for the HTTP User-Agent: request header.
   ///
   /// When null the platform's webview default is used for the User-Agent header.
-  /// Webview user agent for Android (https://developer.chrome.com/multidevice/user-agent)
   ///
-  /// When the [WebView] is rebuilt with a new user agent, the page reloads and the request uses the new User Agent.
+  /// When the [WebView] is rebuilt with a different `userAgent`, the page reloads and the request uses the new User Agent.
   ///
-  /// When [WebViewController.goBack] is called after changing userAgent the previous userAgent value is used until the page is reloaded.
+  /// When [WebViewController.goBack] is called after changing `userAgent` the previous `userAgent` value is used until the page is reloaded.
   ///
-  /// Updating UserAgent is not supported for Flutter WebViews prior to iOS 9.
+  /// This field is ignored on iOS versions prior to 9 as the platform does not support a custom
+  /// user agent.
   ///
   /// By default `userAgent` is null.
   final String userAgent;

From 5be86ef99d408342bf2290f46181f99116f630b3 Mon Sep 17 00:00:00 2001
From: Amir Hardon <amirha@google.com>
Date: Wed, 14 Aug 2019 12:27:13 -0700
Subject: [PATCH 14/20] bump version

---
 packages/webview_flutter/pubspec.yaml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/webview_flutter/pubspec.yaml b/packages/webview_flutter/pubspec.yaml
index d2f6aa0e81e1..6c668033548b 100644
--- a/packages/webview_flutter/pubspec.yaml
+++ b/packages/webview_flutter/pubspec.yaml
@@ -1,6 +1,6 @@
 name: webview_flutter
 description: A Flutter plugin that provides a WebView widget on Android and iOS.
-version: 0.3.11+3
+version: 0.3.12
 author: Flutter Team <flutter-dev@googlegroups.com>
 homepage: https://github.com/flutter/plugins/tree/master/packages/webview_flutter
 

From bf8b74cc16ab2e50e87b2f320199553eac7263cc Mon Sep 17 00:00:00 2001
From: Amir Hardon <amirha@google.com>
Date: Wed, 14 Aug 2019 13:53:50 -0700
Subject: [PATCH 15/20] remove extra blank line from changelog

---
 packages/webview_flutter/CHANGELOG.md | 1 -
 1 file changed, 1 deletion(-)

diff --git a/packages/webview_flutter/CHANGELOG.md b/packages/webview_flutter/CHANGELOG.md
index e8fc547e8c82..d45e0f4e6f6f 100644
--- a/packages/webview_flutter/CHANGELOG.md
+++ b/packages/webview_flutter/CHANGELOG.md
@@ -35,7 +35,6 @@
 
 * Add keyboard text to README.
 
-
 ## 0.3.10+3
 
 * Don't log an unknown setting key error for 'debuggingEnabled' on iOS.

From ebe699d5e15ed47667c9c42edade0cf37f1a9d9e Mon Sep 17 00:00:00 2001
From: Luis Thein <luis.thein@gmx.de>
Date: Thu, 15 Aug 2019 12:05:42 +0200
Subject: [PATCH 16/20] Removed getUserAgent

  - Renoved functions involved in getting the user agent
  - Updated tests to inject javascript to get the current user agent
  - updated changelog
---
 packages/webview_flutter/CHANGELOG.md         |   1 -
 .../webviewflutter/FlutterWebView.java        | 195 +++++++++---------
 .../example/test_driver/webview.dart          |  20 +-
 .../ios/Classes/FlutterWebView.m              |  19 --
 .../lib/platform_interface.dart               |   6 -
 .../lib/src/webview_method_channel.dart       |   5 -
 .../webview_flutter/lib/webview_flutter.dart  |   5 -
 .../test/webview_flutter_test.dart            |  18 --
 8 files changed, 107 insertions(+), 162 deletions(-)

diff --git a/packages/webview_flutter/CHANGELOG.md b/packages/webview_flutter/CHANGELOG.md
index 3da7921d2609..15b4a63dd81b 100644
--- a/packages/webview_flutter/CHANGELOG.md
+++ b/packages/webview_flutter/CHANGELOG.md
@@ -1,7 +1,6 @@
 ## 0.3.12
 
 * Add an optional `userAgent` property to set a custom User Agent.
-* Add `getUserAgent` to WebViewController. 
   
 ## 0.3.11+3
 
diff --git a/packages/webview_flutter/android/src/main/java/io/flutter/plugins/webviewflutter/FlutterWebView.java b/packages/webview_flutter/android/src/main/java/io/flutter/plugins/webviewflutter/FlutterWebView.java
index 4dfcda0f4e7b..fb18036d2abb 100644
--- a/packages/webview_flutter/android/src/main/java/io/flutter/plugins/webviewflutter/FlutterWebView.java
+++ b/packages/webview_flutter/android/src/main/java/io/flutter/plugins/webviewflutter/FlutterWebView.java
@@ -31,16 +31,11 @@ public class FlutterWebView implements PlatformView, MethodCallHandler {
 
   @TargetApi(Build.VERSION_CODES.JELLY_BEAN_MR1)
   @SuppressWarnings("unchecked")
-  FlutterWebView(
-      final Context context,
-      BinaryMessenger messenger,
-      int id,
-      Map<String, Object> params,
+  FlutterWebView(final Context context, BinaryMessenger messenger, int id, Map<String, Object> params,
       final View containerView) {
 
     DisplayListenerProxy displayListenerProxy = new DisplayListenerProxy();
-    DisplayManager displayManager =
-        (DisplayManager) context.getSystemService(Context.DISPLAY_SERVICE);
+    DisplayManager displayManager = (DisplayManager) context.getSystemService(Context.DISPLAY_SERVICE);
     displayListenerProxy.onPreWebViewInitialization(displayManager);
     webView = new InputAwareWebView(context, containerView);
     displayListenerProxy.onPostWebViewInitialization(displayManager);
@@ -76,21 +71,29 @@ public View getView() {
   }
 
   // @Override
-  // This is overriding a method that hasn't rolled into stable Flutter yet. Including the
-  // annotation would cause compile time failures in versions of Flutter too old to include the new
-  // method. However leaving it raw like this means that the method will be ignored in old versions
+  // This is overriding a method that hasn't rolled into stable Flutter yet.
+  // Including the
+  // annotation would cause compile time failures in versions of Flutter too old
+  // to include the new
+  // method. However leaving it raw like this means that the method will be
+  // ignored in old versions
   // of Flutter but used as an override anyway wherever it's actually defined.
-  // TODO(mklim): Add the @Override annotation once flutter/engine#9727 rolls to stable.
+  // TODO(mklim): Add the @Override annotation once flutter/engine#9727 rolls to
+  // stable.
   public void onInputConnectionUnlocked() {
     webView.unlockInputConnection();
   }
 
   // @Override
-  // This is overriding a method that hasn't rolled into stable Flutter yet. Including the
-  // annotation would cause compile time failures in versions of Flutter too old to include the new
-  // method. However leaving it raw like this means that the method will be ignored in old versions
+  // This is overriding a method that hasn't rolled into stable Flutter yet.
+  // Including the
+  // annotation would cause compile time failures in versions of Flutter too old
+  // to include the new
+  // method. However leaving it raw like this means that the method will be
+  // ignored in old versions
   // of Flutter but used as an override anyway wherever it's actually defined.
-  // TODO(mklim): Add the @Override annotation once flutter/engine#9727 rolls to stable.
+  // TODO(mklim): Add the @Override annotation once flutter/engine#9727 rolls to
+  // stable.
   public void onInputConnectionLocked() {
     webView.lockInputConnection();
   }
@@ -98,47 +101,44 @@ public void onInputConnectionLocked() {
   @Override
   public void onMethodCall(MethodCall methodCall, Result result) {
     switch (methodCall.method) {
-      case "loadUrl":
-        loadUrl(methodCall, result);
-        break;
-      case "updateSettings":
-        updateSettings(methodCall, result);
-        break;
-      case "canGoBack":
-        canGoBack(result);
-        break;
-      case "canGoForward":
-        canGoForward(result);
-        break;
-      case "goBack":
-        goBack(result);
-        break;
-      case "goForward":
-        goForward(result);
-        break;
-      case "reload":
-        reload(result);
-        break;
-      case "currentUrl":
-        currentUrl(result);
-        break;
-      case "evaluateJavascript":
-        evaluateJavaScript(methodCall, result);
-        break;
-      case "addJavascriptChannels":
-        addJavaScriptChannels(methodCall, result);
-        break;
-      case "removeJavascriptChannels":
-        removeJavaScriptChannels(methodCall, result);
-        break;
-      case "clearCache":
-        clearCache(result);
-        break;
-      case "getUserAgent":
-        getUserAgent(methodCall, result);
-        break;
-      default:
-        result.notImplemented();
+    case "loadUrl":
+      loadUrl(methodCall, result);
+      break;
+    case "updateSettings":
+      updateSettings(methodCall, result);
+      break;
+    case "canGoBack":
+      canGoBack(result);
+      break;
+    case "canGoForward":
+      canGoForward(result);
+      break;
+    case "goBack":
+      goBack(result);
+      break;
+    case "goForward":
+      goForward(result);
+      break;
+    case "reload":
+      reload(result);
+      break;
+    case "currentUrl":
+      currentUrl(result);
+      break;
+    case "evaluateJavascript":
+      evaluateJavaScript(methodCall, result);
+      break;
+    case "addJavascriptChannels":
+      addJavaScriptChannels(methodCall, result);
+      break;
+    case "removeJavascriptChannels":
+      removeJavaScriptChannels(methodCall, result);
+      break;
+    case "clearCache":
+      clearCache(result);
+      break;
+    default:
+      result.notImplemented();
     }
   }
 
@@ -197,14 +197,12 @@ private void evaluateJavaScript(MethodCall methodCall, final Result result) {
     if (jsString == null) {
       throw new UnsupportedOperationException("JavaScript string cannot be null");
     }
-    webView.evaluateJavascript(
-        jsString,
-        new android.webkit.ValueCallback<String>() {
-          @Override
-          public void onReceiveValue(String value) {
-            result.success(value);
-          }
-        });
+    webView.evaluateJavascript(jsString, new android.webkit.ValueCallback<String>() {
+      @Override
+      public void onReceiveValue(String value) {
+        result.success(value);
+      }
+    });
   }
 
   @SuppressWarnings("unchecked")
@@ -232,46 +230,46 @@ private void clearCache(Result result) {
   private void applySettings(Map<String, Object> settings) {
     for (String key : settings.keySet()) {
       switch (key) {
-        case "jsMode":
-          updateJsMode((Integer) settings.get(key));
-          break;
-        case "hasNavigationDelegate":
-          final boolean hasNavigationDelegate = (boolean) settings.get(key);
-
-          final WebViewClient webViewClient =
-              flutterWebViewClient.createWebViewClient(hasNavigationDelegate);
-
-          webView.setWebViewClient(webViewClient);
-          break;
-        case "debuggingEnabled":
-          final boolean debuggingEnabled = (boolean) settings.get(key);
-
-          webView.setWebContentsDebuggingEnabled(debuggingEnabled);
-          break;
-        case "userAgent":
-          updateUserAgent((String) settings.get(key));
-          break;
-        default:
-          throw new IllegalArgumentException("Unknown WebView setting: " + key);
+      case "jsMode":
+        updateJsMode((Integer) settings.get(key));
+        break;
+      case "hasNavigationDelegate":
+        final boolean hasNavigationDelegate = (boolean) settings.get(key);
+
+        final WebViewClient webViewClient = flutterWebViewClient.createWebViewClient(hasNavigationDelegate);
+
+        webView.setWebViewClient(webViewClient);
+        break;
+      case "debuggingEnabled":
+        final boolean debuggingEnabled = (boolean) settings.get(key);
+
+        webView.setWebContentsDebuggingEnabled(debuggingEnabled);
+        break;
+      case "userAgent":
+        updateUserAgent((String) settings.get(key));
+        break;
+      default:
+        throw new IllegalArgumentException("Unknown WebView setting: " + key);
       }
     }
   }
 
   private void updateJsMode(int mode) {
     switch (mode) {
-      case 0: // disabled
-        webView.getSettings().setJavaScriptEnabled(false);
-        break;
-      case 1: // unrestricted
-        webView.getSettings().setJavaScriptEnabled(true);
-        break;
-      default:
-        throw new IllegalArgumentException("Trying to set unknown JavaScript mode: " + mode);
+    case 0: // disabled
+      webView.getSettings().setJavaScriptEnabled(false);
+      break;
+    case 1: // unrestricted
+      webView.getSettings().setJavaScriptEnabled(true);
+      break;
+    default:
+      throw new IllegalArgumentException("Trying to set unknown JavaScript mode: " + mode);
     }
   }
 
   private void updateAutoMediaPlaybackPolicy(int mode) {
-    // This is the index of the AutoMediaPlaybackPolicy enum, index 1 is always_allow, for all
+    // This is the index of the AutoMediaPlaybackPolicy enum, index 1 is
+    // always_allow, for all
     // other values we require a user gesture.
     boolean requireUserGesture = mode != 1;
     webView.getSettings().setMediaPlaybackRequiresUserGesture(requireUserGesture);
@@ -279,16 +277,11 @@ private void updateAutoMediaPlaybackPolicy(int mode) {
 
   private void registerJavaScriptChannelNames(List<String> channelNames) {
     for (String channelName : channelNames) {
-      webView.addJavascriptInterface(
-          new JavaScriptChannel(methodChannel, channelName, platformThreadHandler), channelName);
+      webView.addJavascriptInterface(new JavaScriptChannel(methodChannel, channelName, platformThreadHandler),
+          channelName);
     }
   }
 
-  private void getUserAgent(MethodCall methodCall, Result result) {
-    String userAgent = webView.getSettings().getUserAgentString();
-    result.success(userAgent);
-  }
-
   private void updateUserAgent(String userAgent) {
     webView.getSettings().setUserAgentString(userAgent);
   }
diff --git a/packages/webview_flutter/example/test_driver/webview.dart b/packages/webview_flutter/example/test_driver/webview.dart
index d347d0e8b737..e16bd1753665 100644
--- a/packages/webview_flutter/example/test_driver/webview.dart
+++ b/packages/webview_flutter/example/test_driver/webview.dart
@@ -241,7 +241,7 @@ void main() {
       ),
     );
     final WebViewController controller1 = await controllerCompleter1.future;
-    final String customUserAgent1 = await controller1.getUserAgent();
+    final String customUserAgent1 = await _getUserAgent(controller1);
     expect(customUserAgent1, 'Custom_User_Agent1');
     // rebuild the WebView with a different user agent.
     await pumpWidget(
@@ -256,7 +256,7 @@ void main() {
       ),
     );
 
-    final String customUserAgent2 = await controller1.getUserAgent();
+    final String customUserAgent2 = await _getUserAgent(controller1);
     expect(customUserAgent2, 'Custom_User_Agent2');
   });
 
@@ -279,7 +279,7 @@ void main() {
       ),
     );
     final WebViewController controller = await controllerCompleter.future;
-    final String defaultPlatformUserAgent = await controller.getUserAgent();
+    final String defaultPlatformUserAgent = await _getUserAgent(controller);
     // rebuild the WebView with a custom user agent.
     await pumpWidget(
       Directionality(
@@ -288,12 +288,12 @@ void main() {
           key: _globalKey,
           initialUrl: 'https://flutter.dev/',
           javascriptMode: JavascriptMode.unrestricted,
-          userAgent: 'Custom_User_Agent',
+          userAgent: 'Custom"_User_"Agent',
         ),
       ),
     );
-    final String customUserAgent = await controller.getUserAgent();
-    expect(customUserAgent, 'Custom_User_Agent');
+    final String customUserAgent = await _getUserAgent(controller);
+    expect(customUserAgent, 'Custom"_User_"Agent');
     // rebuilds the WebView with no user agent.
     await pumpWidget(
       Directionality(
@@ -306,7 +306,7 @@ void main() {
       ),
     );
 
-    final String customUserAgent2 = await controller.getUserAgent();
+    final String customUserAgent2 = await _getUserAgent(controller);
     expect(customUserAgent2, defaultPlatformUserAgent);
   });
 
@@ -472,3 +472,9 @@ String _webviewBool(bool value) {
   }
   return value ? 'true' : 'false';
 }
+
+/// Returns the value used for the HTTP User-Agent: request header in subsequent HTTP requests.
+Future<String> _getUserAgent(WebViewController controller) async {
+  return await controller.evaluateJavascript('navigator.userAgent;')
+    ..toString();
+}
diff --git a/packages/webview_flutter/ios/Classes/FlutterWebView.m b/packages/webview_flutter/ios/Classes/FlutterWebView.m
index 3a9f69be548c..653355b01dfa 100644
--- a/packages/webview_flutter/ios/Classes/FlutterWebView.m
+++ b/packages/webview_flutter/ios/Classes/FlutterWebView.m
@@ -118,8 +118,6 @@ - (void)onMethodCall:(FlutterMethodCall*)call result:(FlutterResult)result {
     [self onRemoveJavaScriptChannels:call result:result];
   } else if ([[call method] isEqualToString:@"clearCache"]) {
     [self clearCache:result];
-  } else if ([[call method] isEqualToString:@"getUserAgent"]) {
-    [self onGetUserAgent:call result:result];
   } else {
     result(FlutterMethodNotImplemented);
   }
@@ -354,23 +352,6 @@ - (void)registerJavaScriptChannels:(NSSet*)channelNames
   }
 }
 
-- (void)onGetUserAgent:(FlutterMethodCall*)call result:(FlutterResult)result {
-  [_webView
-      evaluateJavaScript:@"navigator.userAgent"
-       completionHandler:^(NSString* userAgent, NSError* error) {
-         if (error) {
-           result([FlutterError
-               errorWithCode:@"userAgent_failed"
-                     message:@"Failed to get UserAgent"
-                     details:[NSString stringWithFormat:
-                                           @"webview_flutter: failed evaluating JavaScript: %@",
-                                           [error localizedDescription]]]);
-         } else {
-           result(userAgent);
-         }
-       }];
-}
-
 - (void)updateUserAgent:(NSString*)userAgent {
   if (@available(iOS 9.0, *)) {
     [_webView setCustomUserAgent:userAgent];
diff --git a/packages/webview_flutter/lib/platform_interface.dart b/packages/webview_flutter/lib/platform_interface.dart
index 6b6c518a0689..061b3aa55e66 100644
--- a/packages/webview_flutter/lib/platform_interface.dart
+++ b/packages/webview_flutter/lib/platform_interface.dart
@@ -152,12 +152,6 @@ abstract class WebViewPlatformController {
     throw UnimplementedError(
         "WebView removeJavascriptChannels is not implemented on the current platform");
   }
-
-  /// Returns the value used for the HTTP User-Agent: request header in subsequent HTTP requests.
-  Future<String> getUserAgent() {
-    throw UnimplementedError(
-        "WebView getUserAgent is not implemented on the current platform");
-  }
 }
 
 /// A single setting for configuring a WebViewPlatform which may be absent.
diff --git a/packages/webview_flutter/lib/src/webview_method_channel.dart b/packages/webview_flutter/lib/src/webview_method_channel.dart
index eff948625480..f34000569551 100644
--- a/packages/webview_flutter/lib/src/webview_method_channel.dart
+++ b/packages/webview_flutter/lib/src/webview_method_channel.dart
@@ -103,11 +103,6 @@ class MethodChannelWebViewPlatform implements WebViewPlatformController {
         'removeJavascriptChannels', javascriptChannelNames.toList());
   }
 
-  @override
-  Future<String> getUserAgent() {
-    return _channel.invokeMethod('getUserAgent');
-  }
-
   /// Method channel implementation for [WebViewPlatform.clearCookies].
   static Future<bool> clearCookies() {
     return _cookieManagerChannel
diff --git a/packages/webview_flutter/lib/webview_flutter.dart b/packages/webview_flutter/lib/webview_flutter.dart
index e0345e0c5c5a..97b7786de9a6 100644
--- a/packages/webview_flutter/lib/webview_flutter.dart
+++ b/packages/webview_flutter/lib/webview_flutter.dart
@@ -625,11 +625,6 @@ class WebViewController {
     // ignore: strong_mode_implicit_dynamic_method
     return _webViewPlatformController.evaluateJavascript(javascriptString);
   }
-
-  /// Returns the User Agent value that will be used for subsequent HTTP requests.
-  Future<String> getUserAgent() async {
-    return _webViewPlatformController.getUserAgent();
-  }
 }
 
 /// Manages cookies pertaining to all [WebView]s.
diff --git a/packages/webview_flutter/test/webview_flutter_test.dart b/packages/webview_flutter/test/webview_flutter_test.dart
index 069aede4de45..6907436b24a2 100644
--- a/packages/webview_flutter/test/webview_flutter_test.dart
+++ b/packages/webview_flutter/test/webview_flutter_test.dart
@@ -827,22 +827,6 @@ void main() {
 
     expect(platformWebView.userAgent, 'UA');
   });
-
-  testWidgets('Get UserAgent', (WidgetTester tester) async {
-    WebViewController controller;
-    await tester.pumpWidget(
-      WebView(
-        initialUrl: 'https://youtube.com',
-        javascriptMode: JavascriptMode.unrestricted,
-        userAgent: 'UA',
-        onWebViewCreated: (WebViewController webViewController) {
-          controller = webViewController;
-        },
-      ),
-    );
-    expect(controller, isNotNull);
-    expect(await controller.getUserAgent(), 'UA');
-  });
 }
 
 class FakePlatformWebView {
@@ -936,8 +920,6 @@ class FakePlatformWebView {
       case 'clearCache':
         hasCache = false;
         return Future<void>.sync(() {});
-      case 'getUserAgent':
-        return Future<String>.value(userAgent);
     }
     return Future<void>.sync(() {});
   }

From 641537bc5f889d44f0412844247d82f6b9b595dd Mon Sep 17 00:00:00 2001
From: Luis Thein <luis.thein@gmx.de>
Date: Thu, 15 Aug 2019 12:29:39 +0200
Subject: [PATCH 17/20] Fixed formatting issue

---
 .../webviewflutter/FlutterWebView.java        | 160 +++++++++---------
 .../example/test_driver/webview.dart          |   2 +-
 2 files changed, 85 insertions(+), 77 deletions(-)

diff --git a/packages/webview_flutter/android/src/main/java/io/flutter/plugins/webviewflutter/FlutterWebView.java b/packages/webview_flutter/android/src/main/java/io/flutter/plugins/webviewflutter/FlutterWebView.java
index fb18036d2abb..c18b2535e78a 100644
--- a/packages/webview_flutter/android/src/main/java/io/flutter/plugins/webviewflutter/FlutterWebView.java
+++ b/packages/webview_flutter/android/src/main/java/io/flutter/plugins/webviewflutter/FlutterWebView.java
@@ -31,11 +31,16 @@ public class FlutterWebView implements PlatformView, MethodCallHandler {
 
   @TargetApi(Build.VERSION_CODES.JELLY_BEAN_MR1)
   @SuppressWarnings("unchecked")
-  FlutterWebView(final Context context, BinaryMessenger messenger, int id, Map<String, Object> params,
+  FlutterWebView(
+      final Context context,
+      BinaryMessenger messenger,
+      int id,
+      Map<String, Object> params,
       final View containerView) {
 
     DisplayListenerProxy displayListenerProxy = new DisplayListenerProxy();
-    DisplayManager displayManager = (DisplayManager) context.getSystemService(Context.DISPLAY_SERVICE);
+    DisplayManager displayManager =
+        (DisplayManager) context.getSystemService(Context.DISPLAY_SERVICE);
     displayListenerProxy.onPreWebViewInitialization(displayManager);
     webView = new InputAwareWebView(context, containerView);
     displayListenerProxy.onPostWebViewInitialization(displayManager);
@@ -101,44 +106,44 @@ public void onInputConnectionLocked() {
   @Override
   public void onMethodCall(MethodCall methodCall, Result result) {
     switch (methodCall.method) {
-    case "loadUrl":
-      loadUrl(methodCall, result);
-      break;
-    case "updateSettings":
-      updateSettings(methodCall, result);
-      break;
-    case "canGoBack":
-      canGoBack(result);
-      break;
-    case "canGoForward":
-      canGoForward(result);
-      break;
-    case "goBack":
-      goBack(result);
-      break;
-    case "goForward":
-      goForward(result);
-      break;
-    case "reload":
-      reload(result);
-      break;
-    case "currentUrl":
-      currentUrl(result);
-      break;
-    case "evaluateJavascript":
-      evaluateJavaScript(methodCall, result);
-      break;
-    case "addJavascriptChannels":
-      addJavaScriptChannels(methodCall, result);
-      break;
-    case "removeJavascriptChannels":
-      removeJavaScriptChannels(methodCall, result);
-      break;
-    case "clearCache":
-      clearCache(result);
-      break;
-    default:
-      result.notImplemented();
+      case "loadUrl":
+        loadUrl(methodCall, result);
+        break;
+      case "updateSettings":
+        updateSettings(methodCall, result);
+        break;
+      case "canGoBack":
+        canGoBack(result);
+        break;
+      case "canGoForward":
+        canGoForward(result);
+        break;
+      case "goBack":
+        goBack(result);
+        break;
+      case "goForward":
+        goForward(result);
+        break;
+      case "reload":
+        reload(result);
+        break;
+      case "currentUrl":
+        currentUrl(result);
+        break;
+      case "evaluateJavascript":
+        evaluateJavaScript(methodCall, result);
+        break;
+      case "addJavascriptChannels":
+        addJavaScriptChannels(methodCall, result);
+        break;
+      case "removeJavascriptChannels":
+        removeJavaScriptChannels(methodCall, result);
+        break;
+      case "clearCache":
+        clearCache(result);
+        break;
+      default:
+        result.notImplemented();
     }
   }
 
@@ -197,12 +202,14 @@ private void evaluateJavaScript(MethodCall methodCall, final Result result) {
     if (jsString == null) {
       throw new UnsupportedOperationException("JavaScript string cannot be null");
     }
-    webView.evaluateJavascript(jsString, new android.webkit.ValueCallback<String>() {
-      @Override
-      public void onReceiveValue(String value) {
-        result.success(value);
-      }
-    });
+    webView.evaluateJavascript(
+        jsString,
+        new android.webkit.ValueCallback<String>() {
+          @Override
+          public void onReceiveValue(String value) {
+            result.success(value);
+          }
+        });
   }
 
   @SuppressWarnings("unchecked")
@@ -230,40 +237,41 @@ private void clearCache(Result result) {
   private void applySettings(Map<String, Object> settings) {
     for (String key : settings.keySet()) {
       switch (key) {
-      case "jsMode":
-        updateJsMode((Integer) settings.get(key));
-        break;
-      case "hasNavigationDelegate":
-        final boolean hasNavigationDelegate = (boolean) settings.get(key);
-
-        final WebViewClient webViewClient = flutterWebViewClient.createWebViewClient(hasNavigationDelegate);
-
-        webView.setWebViewClient(webViewClient);
-        break;
-      case "debuggingEnabled":
-        final boolean debuggingEnabled = (boolean) settings.get(key);
-
-        webView.setWebContentsDebuggingEnabled(debuggingEnabled);
-        break;
-      case "userAgent":
-        updateUserAgent((String) settings.get(key));
-        break;
-      default:
-        throw new IllegalArgumentException("Unknown WebView setting: " + key);
+        case "jsMode":
+          updateJsMode((Integer) settings.get(key));
+          break;
+        case "hasNavigationDelegate":
+          final boolean hasNavigationDelegate = (boolean) settings.get(key);
+
+          final WebViewClient webViewClient =
+              flutterWebViewClient.createWebViewClient(hasNavigationDelegate);
+
+          webView.setWebViewClient(webViewClient);
+          break;
+        case "debuggingEnabled":
+          final boolean debuggingEnabled = (boolean) settings.get(key);
+
+          webView.setWebContentsDebuggingEnabled(debuggingEnabled);
+          break;
+        case "userAgent":
+          updateUserAgent((String) settings.get(key));
+          break;
+        default:
+          throw new IllegalArgumentException("Unknown WebView setting: " + key);
       }
     }
   }
 
   private void updateJsMode(int mode) {
     switch (mode) {
-    case 0: // disabled
-      webView.getSettings().setJavaScriptEnabled(false);
-      break;
-    case 1: // unrestricted
-      webView.getSettings().setJavaScriptEnabled(true);
-      break;
-    default:
-      throw new IllegalArgumentException("Trying to set unknown JavaScript mode: " + mode);
+      case 0: // disabled
+        webView.getSettings().setJavaScriptEnabled(false);
+        break;
+      case 1: // unrestricted
+        webView.getSettings().setJavaScriptEnabled(true);
+        break;
+      default:
+        throw new IllegalArgumentException("Trying to set unknown JavaScript mode: " + mode);
     }
   }
 
@@ -277,8 +285,8 @@ private void updateAutoMediaPlaybackPolicy(int mode) {
 
   private void registerJavaScriptChannelNames(List<String> channelNames) {
     for (String channelName : channelNames) {
-      webView.addJavascriptInterface(new JavaScriptChannel(methodChannel, channelName, platformThreadHandler),
-          channelName);
+      webView.addJavascriptInterface(
+          new JavaScriptChannel(methodChannel, channelName, platformThreadHandler), channelName);
     }
   }
 
diff --git a/packages/webview_flutter/example/test_driver/webview.dart b/packages/webview_flutter/example/test_driver/webview.dart
index e16bd1753665..83f28f37e180 100644
--- a/packages/webview_flutter/example/test_driver/webview.dart
+++ b/packages/webview_flutter/example/test_driver/webview.dart
@@ -293,7 +293,7 @@ void main() {
       ),
     );
     final String customUserAgent = await _getUserAgent(controller);
-    expect(customUserAgent, 'Custom"_User_"Agent');
+    expect(customUserAgent, 'Custom_User_Agent');
     // rebuilds the WebView with no user agent.
     await pumpWidget(
       Directionality(

From db3cfb966009429c34d62e0acb2abfae0a7cccaf Mon Sep 17 00:00:00 2001
From: Luis Thein <luis.thein@gmx.de>
Date: Thu, 15 Aug 2019 12:56:57 +0200
Subject: [PATCH 18/20] Fixed _getUserAgent in webview.dart

---
 .../webview_flutter/example/test_driver/webview.dart     | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/packages/webview_flutter/example/test_driver/webview.dart b/packages/webview_flutter/example/test_driver/webview.dart
index 83f28f37e180..be7e859df27c 100644
--- a/packages/webview_flutter/example/test_driver/webview.dart
+++ b/packages/webview_flutter/example/test_driver/webview.dart
@@ -288,7 +288,7 @@ void main() {
           key: _globalKey,
           initialUrl: 'https://flutter.dev/',
           javascriptMode: JavascriptMode.unrestricted,
-          userAgent: 'Custom"_User_"Agent',
+          userAgent: 'Custom_User_Agent',
         ),
       ),
     );
@@ -475,6 +475,9 @@ String _webviewBool(bool value) {
 
 /// Returns the value used for the HTTP User-Agent: request header in subsequent HTTP requests.
 Future<String> _getUserAgent(WebViewController controller) async {
-  return await controller.evaluateJavascript('navigator.userAgent;')
-    ..toString();
+  if (defaultTargetPlatform == TargetPlatform.iOS) {
+    return await controller.evaluateJavascript('navigator.userAgent;');
+  }
+  return jsonDecode(
+      await controller.evaluateJavascript('navigator.userAgent;'));
 }

From 974c16e0d026e6e0b94ccce707ba2e176adbb697 Mon Sep 17 00:00:00 2001
From: Luis Thein <luis.thein@gmx.de>
Date: Fri, 16 Aug 2019 18:52:56 +0200
Subject: [PATCH 19/20] Reverted unrelated reformatting

---
 .../webviewflutter/FlutterWebView.java        | 59 ++++++++-----------
 1 file changed, 25 insertions(+), 34 deletions(-)

diff --git a/packages/webview_flutter/android/src/main/java/io/flutter/plugins/webviewflutter/FlutterWebView.java b/packages/webview_flutter/android/src/main/java/io/flutter/plugins/webviewflutter/FlutterWebView.java
index c18b2535e78a..219d54d2df10 100644
--- a/packages/webview_flutter/android/src/main/java/io/flutter/plugins/webviewflutter/FlutterWebView.java
+++ b/packages/webview_flutter/android/src/main/java/io/flutter/plugins/webviewflutter/FlutterWebView.java
@@ -32,15 +32,15 @@ public class FlutterWebView implements PlatformView, MethodCallHandler {
   @TargetApi(Build.VERSION_CODES.JELLY_BEAN_MR1)
   @SuppressWarnings("unchecked")
   FlutterWebView(
-      final Context context,
-      BinaryMessenger messenger,
-      int id,
-      Map<String, Object> params,
-      final View containerView) {
+          final Context context,
+          BinaryMessenger messenger,
+          int id,
+          Map<String, Object> params,
+          final View containerView) {
 
     DisplayListenerProxy displayListenerProxy = new DisplayListenerProxy();
     DisplayManager displayManager =
-        (DisplayManager) context.getSystemService(Context.DISPLAY_SERVICE);
+            (DisplayManager) context.getSystemService(Context.DISPLAY_SERVICE);
     displayListenerProxy.onPreWebViewInitialization(displayManager);
     webView = new InputAwareWebView(context, containerView);
     displayListenerProxy.onPostWebViewInitialization(displayManager);
@@ -76,29 +76,21 @@ public View getView() {
   }
 
   // @Override
-  // This is overriding a method that hasn't rolled into stable Flutter yet.
-  // Including the
-  // annotation would cause compile time failures in versions of Flutter too old
-  // to include the new
-  // method. However leaving it raw like this means that the method will be
-  // ignored in old versions
+  // This is overriding a method that hasn't rolled into stable Flutter yet. Including the
+  // annotation would cause compile time failures in versions of Flutter too old to include the new
+  // method. However leaving it raw like this means that the method will be ignored in old versions
   // of Flutter but used as an override anyway wherever it's actually defined.
-  // TODO(mklim): Add the @Override annotation once flutter/engine#9727 rolls to
-  // stable.
+  // TODO(mklim): Add the @Override annotation once flutter/engine#9727 rolls to stable.
   public void onInputConnectionUnlocked() {
     webView.unlockInputConnection();
   }
 
   // @Override
-  // This is overriding a method that hasn't rolled into stable Flutter yet.
-  // Including the
-  // annotation would cause compile time failures in versions of Flutter too old
-  // to include the new
-  // method. However leaving it raw like this means that the method will be
-  // ignored in old versions
+  // This is overriding a method that hasn't rolled into stable Flutter yet. Including the
+  // annotation would cause compile time failures in versions of Flutter too old to include the new
+  // method. However leaving it raw like this means that the method will be ignored in old versions
   // of Flutter but used as an override anyway wherever it's actually defined.
-  // TODO(mklim): Add the @Override annotation once flutter/engine#9727 rolls to
-  // stable.
+  // TODO(mklim): Add the @Override annotation once flutter/engine#9727 rolls to stable.
   public void onInputConnectionLocked() {
     webView.lockInputConnection();
   }
@@ -203,13 +195,13 @@ private void evaluateJavaScript(MethodCall methodCall, final Result result) {
       throw new UnsupportedOperationException("JavaScript string cannot be null");
     }
     webView.evaluateJavascript(
-        jsString,
-        new android.webkit.ValueCallback<String>() {
-          @Override
-          public void onReceiveValue(String value) {
-            result.success(value);
-          }
-        });
+            jsString,
+            new android.webkit.ValueCallback<String>() {
+              @Override
+              public void onReceiveValue(String value) {
+                result.success(value);
+              }
+            });
   }
 
   @SuppressWarnings("unchecked")
@@ -244,7 +236,7 @@ private void applySettings(Map<String, Object> settings) {
           final boolean hasNavigationDelegate = (boolean) settings.get(key);
 
           final WebViewClient webViewClient =
-              flutterWebViewClient.createWebViewClient(hasNavigationDelegate);
+                  flutterWebViewClient.createWebViewClient(hasNavigationDelegate);
 
           webView.setWebViewClient(webViewClient);
           break;
@@ -276,8 +268,7 @@ private void updateJsMode(int mode) {
   }
 
   private void updateAutoMediaPlaybackPolicy(int mode) {
-    // This is the index of the AutoMediaPlaybackPolicy enum, index 1 is
-    // always_allow, for all
+    // This is the index of the AutoMediaPlaybackPolicy enum, index 1 is always_allow, for all
     // other values we require a user gesture.
     boolean requireUserGesture = mode != 1;
     webView.getSettings().setMediaPlaybackRequiresUserGesture(requireUserGesture);
@@ -286,7 +277,7 @@ private void updateAutoMediaPlaybackPolicy(int mode) {
   private void registerJavaScriptChannelNames(List<String> channelNames) {
     for (String channelName : channelNames) {
       webView.addJavascriptInterface(
-          new JavaScriptChannel(methodChannel, channelName, platformThreadHandler), channelName);
+              new JavaScriptChannel(methodChannel, channelName, platformThreadHandler), channelName);
     }
   }
 
@@ -299,4 +290,4 @@ public void dispose() {
     methodChannel.setMethodCallHandler(null);
     webView.dispose();
   }
-}
+}
\ No newline at end of file

From 3282117f40828692453254d4b473e22ecf7e6cad Mon Sep 17 00:00:00 2001
From: Luis Thein <luis.thein@gmx.de>
Date: Fri, 16 Aug 2019 19:12:40 +0200
Subject: [PATCH 20/20] Fixed another formatting issue.

---
 .../webviewflutter/FlutterWebView.java        | 32 +++++++++----------
 1 file changed, 16 insertions(+), 16 deletions(-)

diff --git a/packages/webview_flutter/android/src/main/java/io/flutter/plugins/webviewflutter/FlutterWebView.java b/packages/webview_flutter/android/src/main/java/io/flutter/plugins/webviewflutter/FlutterWebView.java
index 0470bf442316..2288b8f52d5a 100644
--- a/packages/webview_flutter/android/src/main/java/io/flutter/plugins/webviewflutter/FlutterWebView.java
+++ b/packages/webview_flutter/android/src/main/java/io/flutter/plugins/webviewflutter/FlutterWebView.java
@@ -32,15 +32,15 @@ public class FlutterWebView implements PlatformView, MethodCallHandler {
   @TargetApi(Build.VERSION_CODES.JELLY_BEAN_MR1)
   @SuppressWarnings("unchecked")
   FlutterWebView(
-          final Context context,
-          BinaryMessenger messenger,
-          int id,
-          Map<String, Object> params,
-          final View containerView) {
+      final Context context,
+      BinaryMessenger messenger,
+      int id,
+      Map<String, Object> params,
+      final View containerView) {
 
     DisplayListenerProxy displayListenerProxy = new DisplayListenerProxy();
     DisplayManager displayManager =
-            (DisplayManager) context.getSystemService(Context.DISPLAY_SERVICE);
+        (DisplayManager) context.getSystemService(Context.DISPLAY_SERVICE);
     displayListenerProxy.onPreWebViewInitialization(displayManager);
     webView = new InputAwareWebView(context, containerView);
     displayListenerProxy.onPostWebViewInitialization(displayManager);
@@ -195,13 +195,13 @@ private void evaluateJavaScript(MethodCall methodCall, final Result result) {
       throw new UnsupportedOperationException("JavaScript string cannot be null");
     }
     webView.evaluateJavascript(
-            jsString,
-            new android.webkit.ValueCallback<String>() {
-              @Override
-              public void onReceiveValue(String value) {
-                result.success(value);
-              }
-            });
+        jsString,
+        new android.webkit.ValueCallback<String>() {
+          @Override
+          public void onReceiveValue(String value) {
+            result.success(value);
+          }
+        });
   }
 
   @SuppressWarnings("unchecked")
@@ -236,7 +236,7 @@ private void applySettings(Map<String, Object> settings) {
           final boolean hasNavigationDelegate = (boolean) settings.get(key);
 
           final WebViewClient webViewClient =
-                  flutterWebViewClient.createWebViewClient(hasNavigationDelegate);
+              flutterWebViewClient.createWebViewClient(hasNavigationDelegate);
 
           webView.setWebViewClient(webViewClient);
           break;
@@ -277,7 +277,7 @@ private void updateAutoMediaPlaybackPolicy(int mode) {
   private void registerJavaScriptChannelNames(List<String> channelNames) {
     for (String channelName : channelNames) {
       webView.addJavascriptInterface(
-              new JavaScriptChannel(methodChannel, channelName, platformThreadHandler), channelName);
+          new JavaScriptChannel(methodChannel, channelName, platformThreadHandler), channelName);
     }
   }
 
@@ -291,4 +291,4 @@ public void dispose() {
     webView.dispose();
     webView.destroy();
   }
-}
\ No newline at end of file
+}