Add support for universal banner messages

packages/devtools_app/lib/src/shared/managers/banner_messages.dart

@@ -23,6 +23,13 @@ const _runInProfileModeDocsUrl = 'https://flutter.dev/to/use-profile-mode';
 const _cpuSamplingRateDocsUrl =
     'https://docs.flutter.dev/tools/devtools/cpu-profiler#cpu-sampling-rate';
 
+/// Screen id to use for banner messages that are intended to be universal for
+/// every DevTools screen.
+///
+/// Messages with this screen id will be added to the list of messages for
+/// every screen from the [BannerMessages] widget.
+const universalBannerMessageId = 'universal';
+
 class BannerMessagesController {
   final _messages = <String, ListValueNotifier<BannerMessage>>{};
   final _dismissedMessageKeys = <Key?>{};
@@ -77,13 +84,13 @@ class BannerMessagesController {
     });
   }
 
-  void removeMessageByKey(Key key, String screenId) {
+  void removeMessageByKey(Key key, String screenId, {bool dismiss = false}) {
     final currentMessages = _messagesForScreen(screenId);
     final messageWithKey = currentMessages.value.firstWhereOrNull(
       (m) => m.key == key,
     );
     if (messageWithKey != null) {
-      removeMessage(messageWithKey);
+      removeMessage(messageWithKey, dismiss: dismiss);
     }
   }
 
@@ -119,13 +126,18 @@ class BannerMessages extends StatelessWidget {
   // TODO(kenz): use an AnimatedList for message changes.
   @override
   Widget build(BuildContext context) {
+    final universalMessages = bannerMessages.messagesForScreen(
+      universalBannerMessageId,
+    );
     final messagesForScreen = bannerMessages.messagesForScreen(screen.screenId);
     return Column(
       children: [
-        ValueListenableBuilder<List<BannerMessage>>(
-          valueListenable: messagesForScreen,
-          builder: (context, messages, _) {
-            return Column(children: messages);
+        MultiValueListenableBuilder(
+          listenables: [universalMessages, messagesForScreen],
+          builder: (context, values, _) {
+            final universalMessages = values[0] as List<BannerMessage>;
+            final messages = values[1] as List<BannerMessage>;
+            return Column(children: [...universalMessages, ...messages]);
           },
         ),
         Expanded(child: screen.build(context)),

packages/devtools_app/test/shared/managers/banner_messages_test.dart

@@ -2,11 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file or at https://developers.google.com/open-source/licenses/bsd.
 
+import 'package:devtools_app/devtools_app.dart';
 import 'package:devtools_app/src/framework/scaffold/scaffold.dart';
-import 'package:devtools_app/src/service/service_manager.dart';
-import 'package:devtools_app/src/shared/globals.dart';
-import 'package:devtools_app/src/shared/managers/banner_messages.dart';
-import 'package:devtools_app/src/shared/managers/notifications.dart';
 import 'package:devtools_app_shared/ui.dart';
 import 'package:devtools_app_shared/utils.dart';
 import 'package:devtools_test/devtools_test.dart';
@@ -34,20 +31,12 @@ void main() {
       await tester.pumpAndSettle();
     }
 
-    Widget buildBannerMessages() {
+    Widget buildBannerMessages({Screen? screen}) {
       return wrap(
         Directionality(
           textDirection: TextDirection.ltr,
           child: BannerMessages(
-            screen: SimpleScreen(
-              Column(
-                children: <Widget>[
-                  // This is button is present so that we can tap it and
-                  // simulate a frame being drawn.
-                  ElevatedButton(onPressed: () => {}, child: const SizedBox()),
-                ],
-              ),
-            ),
+            screen: screen ?? SimpleScreen(const _TestScreenBody()),
           ),
         ),
       );
@@ -66,6 +55,18 @@ void main() {
       expect(find.byKey(k2), findsOneWidget);
     });
 
+    testWidgets('displays universal banner messages for every screen', (
+      WidgetTester tester,
+    ) async {
+      await tester.pumpWidget(buildBannerMessages());
+      bannerMessages.addMessage(universalMessage);
+      await pumpTestFrame(tester);
+      expect(find.byKey(kUniversal), findsOneWidget);
+
+      await tester.pumpWidget(buildBannerMessages(screen: TestScreen()));
+      expect(find.byKey(kUniversal), findsOneWidget);
+    });
+
     testWidgets('does not add duplicate messages', (WidgetTester tester) async {
       await tester.pumpWidget(buildBannerMessages());
       expect(find.byKey(k1), findsNothing);
@@ -164,17 +165,56 @@ void main() {
 
 final testMessage1ScreenId = SimpleScreen.id;
 final testMessage2ScreenId = SimpleScreen.id;
+
 const k1 = Key('test message 1');
 const k2 = Key('test message 2');
+const kUniversal = Key('universal message');
+
 final testMessage1 = BannerMessage(
   key: k1,
   buildTextSpans: (_) => const [TextSpan(text: 'Test Message 1')],
   screenId: testMessage1ScreenId,
   messageType: BannerMessageType.warning,
 );
+
 final testMessage2 = BannerMessage(
   key: k2,
   buildTextSpans: (_) => const [TextSpan(text: 'Test Message 2')],
   screenId: testMessage2ScreenId,
   messageType: BannerMessageType.warning,
 );
+
+final universalMessage = BannerMessage(
+  key: kUniversal,
+  buildTextSpans: (_) => const [TextSpan(text: 'Universal Message')],
+  screenId: universalBannerMessageId,
+  messageType: BannerMessageType.warning,
+);
+
+class TestScreen extends Screen {
+  TestScreen() : super(id, showFloatingDebuggerControls: false);
+
+  // This is arbitrary for the test. It just needs to be something different
+  // than [ScreenMetaData.simple.id].
+  static final id = ScreenMetaData.logging.id;
+
+  @override
+  Widget buildScreenBody(BuildContext context) {
+    return const _TestScreenBody();
+  }
+}
+
+class _TestScreenBody extends StatelessWidget {
+  const _TestScreenBody();
+
+  @override
+  Widget build(BuildContext context) {
+    return Column(
+      children: <Widget>[
+        // This button is present so that we can tap it and
+        // simulate a frame being drawn.
+        ElevatedButton(onPressed: () => {}, child: const SizedBox()),
+      ],
+    );
+  }
+}