[url_launcher] Remove renderView usage

Removes calls to the deprecated `renderView` method, replacing them with
best-effort lookup of the implicit view. This only affects an API that
has been deprecated for almost two years, and only when using a specific
optional parameter on that method, so the potential impact here is
minimal, and this avoids the need for a breaking change.

In the future, when we remove this deprecated API, the workaround will
go away as well.

Fixes flutter/flutter#143449

packages/url_launcher/url_launcher/lib/src/legacy_api.dart

@@ -3,8 +3,10 @@
 // found in the LICENSE file.
 
 import 'dart:async';
+import 'dart:ui';
 
 import 'package:flutter/foundation.dart';
+import 'package:flutter/rendering.dart';
 import 'package:flutter/services.dart';
 import 'package:flutter/widgets.dart';
 import 'package:url_launcher_platform_interface/url_launcher_platform_interface.dart';
@@ -85,15 +87,14 @@ Future<bool> launch(
 
   /// [true] so that ui is automatically computed if [statusBarBrightness] is set.
   bool previousAutomaticSystemUiAdjustment = true;
-  if (statusBarBrightness != null &&
-      defaultTargetPlatform == TargetPlatform.iOS &&
-      _ambiguate(WidgetsBinding.instance) != null) {
-    previousAutomaticSystemUiAdjustment = _ambiguate(WidgetsBinding.instance)!
-        .renderView
-        .automaticSystemUiAdjustment;
-    _ambiguate(WidgetsBinding.instance)!
-        .renderView
-        .automaticSystemUiAdjustment = false;
+  final RenderView? renderViewToAdjust =
+      statusBarBrightness != null && defaultTargetPlatform == TargetPlatform.iOS
+          ? _findImplicitRenderView()
+          : null;
+  if (renderViewToAdjust != null) {
+    previousAutomaticSystemUiAdjustment =
+        renderViewToAdjust.automaticSystemUiAdjustment;
+    renderViewToAdjust.automaticSystemUiAdjustment = false;
     SystemChrome.setSystemUIOverlayStyle(statusBarBrightness == Brightness.light
         ? SystemUiOverlayStyle.dark
         : SystemUiOverlayStyle.light);
@@ -110,11 +111,9 @@ Future<bool> launch(
     webOnlyWindowName: webOnlyWindowName,
   );
 
-  if (statusBarBrightness != null &&
-      _ambiguate(WidgetsBinding.instance) != null) {
-    _ambiguate(WidgetsBinding.instance)!
-        .renderView
-        .automaticSystemUiAdjustment = previousAutomaticSystemUiAdjustment;
+  if (renderViewToAdjust != null) {
+    renderViewToAdjust.automaticSystemUiAdjustment =
+        previousAutomaticSystemUiAdjustment;
   }
 
   return result;
@@ -146,8 +145,22 @@ Future<void> closeWebView() async {
   return UrlLauncherPlatform.instance.closeWebView();
 }
 
-/// This allows a value of type T or T? to be treated as a value of type T?.
+/// Returns the [RenderView] associated with the implicit [FlutterView], if any.
 ///
-/// We use this so that APIs that have become non-nullable can still be used
-/// with `!` and `?` on the stable branch.
-T? _ambiguate<T>(T? value) => value;
+/// [launch] predates multi-window support, and it doesn't have enough context
+/// to get the right render view, so this assumes anyone still trying to use
+/// the deprecated API with `statusBarBrightness` is in a single-view scenario.
+/// This allows a best-effort implementation of the deprecated API for as long
+/// as it continues to exist, without depending on deprecated Flutter APIs (and
+/// therefore keeping url_launcher forward-compatible with future versions of
+/// Flutter for longer).
+RenderView? _findImplicitRenderView() {
+  final FlutterView? implicitFlutteView =
+      WidgetsBinding.instance.platformDispatcher.implicitView;
+  if (implicitFlutteView == null) {
+    return null;
+  }
+  return WidgetsBinding.instance.renderViews
+      .where((RenderView v) => v.flutterView == implicitFlutteView)
+      .firstOrNull;
+}

packages/url_launcher/url_launcher/test/src/legacy_api_test.dart

@@ -235,10 +235,11 @@ void main() {
         ..setResponse(true);
 
       final TestWidgetsFlutterBinding binding =
-          _anonymize(TestWidgetsFlutterBinding.ensureInitialized())!
-              as TestWidgetsFlutterBinding;
+          TestWidgetsFlutterBinding.ensureInitialized();
       debugDefaultTargetPlatformOverride = TargetPlatform.iOS;
-      final RenderView renderView = binding.renderView;
+      final RenderView renderView =
+          RenderView(view: binding.platformDispatcher.implicitView!);
+      binding.addRenderView(renderView);
       renderView.automaticSystemUiAdjustment = true;
       final Future<bool> launchResult =
           launch('http://flutter.dev/', statusBarBrightness: Brightness.dark);
@@ -248,6 +249,7 @@ void main() {
       expect(renderView.automaticSystemUiAdjustment, isFalse);
       await launchResult;
       expect(renderView.automaticSystemUiAdjustment, isTrue);
+      binding.removeRenderView(renderView);
     });
 
     test('sets automaticSystemUiAdjustment to not be null', () async {
@@ -265,10 +267,11 @@ void main() {
         ..setResponse(true);
 
       final TestWidgetsFlutterBinding binding =
-          _anonymize(TestWidgetsFlutterBinding.ensureInitialized())!
-              as TestWidgetsFlutterBinding;
+          TestWidgetsFlutterBinding.ensureInitialized();
       debugDefaultTargetPlatformOverride = TargetPlatform.android;
-      final RenderView renderView = binding.renderView;
+      final RenderView renderView =
+          RenderView(view: binding.platformDispatcher.implicitView!);
+      binding.addRenderView(renderView);
       expect(renderView.automaticSystemUiAdjustment, true);
       final Future<bool> launchResult =
           launch('http://flutter.dev/', statusBarBrightness: Brightness.dark);
@@ -278,6 +281,7 @@ void main() {
       expect(renderView.automaticSystemUiAdjustment, true);
       await launchResult;
       expect(renderView.automaticSystemUiAdjustment, true);
+      binding.removeRenderView(renderView);
     });
 
     test('open non-parseable url', () async {
@@ -317,9 +321,3 @@ void main() {
     });
   });
 }
-
-/// This removes the type information from a value so that it can be cast
-/// to another type even if that cast is redundant.
-/// We use this so that APIs whose type have become more descriptive can still
-/// be used on the stable branch where they require a cast.
-Object? _anonymize<T>(T? value) => value;