Removes unused code in DevTools app `extensions/` and `framework/` directories (#9909) Work towards https://github.com/flutter/devtools/issues/9906 Chained on top of https://github.com/flutter/devtools/pull/9908

diff --git a/analysis_options.yaml b/analysis_options.yaml
index d6dd068..e57f4c2 100644
--- a/analysis_options.yaml
+++ b/analysis_options.yaml

@@ -164,8 +164,6 @@
       # TODO(https://github.com/flutter/devtools/issues/9906) remove these
       # excludes as findings are resolved.
       - integration_test/**
-      - lib/src/extensions/**
-      - lib/src/framework/**
       - lib/src/screens/**
       - lib/src/service/**
       - lib/src/shared/**

diff --git a/packages/devtools_app/lib/src/extensions/embedded/_controller_web.dart b/packages/devtools_app/lib/src/extensions/embedded/_controller_web.dart
index 388fe7a..1da1d18 100644
--- a/packages/devtools_app/lib/src/extensions/embedded/_controller_web.dart
+++ b/packages/devtools_app/lib/src/extensions/embedded/_controller_web.dart

@@ -78,6 +78,7 @@
   final extensionPostEventStream =
       StreamController<DevToolsExtensionEvent>.broadcast();
 
+  // ignore: unused-code, TODO(https://github.com/flutter/devtools/issues/9907): false positive.
   bool _initialized = false;
 
   @override

diff --git a/packages/devtools_app/lib/src/extensions/embedded/_view_desktop.dart b/packages/devtools_app/lib/src/extensions/embedded/_view_desktop.dart
index 5d9403f..051461b 100644
--- a/packages/devtools_app/lib/src/extensions/embedded/_view_desktop.dart
+++ b/packages/devtools_app/lib/src/extensions/embedded/_view_desktop.dart

@@ -7,9 +7,10 @@
 import 'controller.dart';
 
 class EmbeddedExtension extends StatelessWidget {
-  const EmbeddedExtension({super.key, required this.controller});
-
-  final EmbeddedExtensionController controller;
+  const EmbeddedExtension({
+    super.key,
+    required EmbeddedExtensionController controller,
+  });
 
   @override
   Widget build(BuildContext context) {

diff --git a/packages/devtools_app/lib/src/extensions/extension_service.dart b/packages/devtools_app/lib/src/extensions/extension_service.dart
index 2c7513b..ae49a3b 100644
--- a/packages/devtools_app/lib/src/extensions/extension_service.dart
+++ b/packages/devtools_app/lib/src/extensions/extension_service.dart

@@ -70,6 +70,7 @@
   ///
   /// This set of extensions will include one version of a DevTools extension
   /// per package.
+  @visibleForTesting
   List<DevToolsExtensionConfig> get availableExtensions =>
       _currentExtensions.value.availableExtensions;
 

diff --git a/packages/devtools_app/lib/src/framework/home_screen.dart b/packages/devtools_app/lib/src/framework/home_screen.dart
index 7b02646..6da52cb 100644
--- a/packages/devtools_app/lib/src/framework/home_screen.dart
+++ b/packages/devtools_app/lib/src/framework/home_screen.dart

@@ -32,8 +32,6 @@
         titleGenerator: () => devToolsTitle.value,
       );
 
-  static final id = ScreenMetaData.home.id;
-
   final List<DevToolsJsonFile> sampleData;
 
   @override
@@ -165,10 +163,7 @@
   void initState() {
     super.initState();
     connectDialogController = TextEditingController();
-    assert(() {
-      _debugInitVmServiceCache();
-      return true;
-    }());
+    if (kDebugMode) _debugInitVmServiceCache();
   }
 
   void _debugInitVmServiceCache() async {
@@ -176,7 +171,7 @@
     // developers who tend to repeatedly restart DevTools to debug the same
     // test application.
     final uri = await storage.getValue(_debugVmServiceUriKey);
-    if (uri != null) {
+    if (uri != null && mounted) {
       setState(() {
         connectDialogController.text = uri;
       });
@@ -258,10 +253,9 @@
       return;
     }
 
-    assert(() {
+    if (kDebugMode) {
       safeUnawaited(storage.setValue(_debugVmServiceUriKey, uri));
-      return true;
-    }());
+    }
 
     // Cache the routerDelegate and notifications providers before the async
     // gap as the landing screen may not be displayed by the time the async gap

diff --git a/packages/devtools_app/lib/src/framework/release_notes.dart b/packages/devtools_app/lib/src/framework/release_notes.dart
index f6ea52c..f7632c6 100644
--- a/packages/devtools_app/lib/src/framework/release_notes.dart
+++ b/packages/devtools_app/lib/src/framework/release_notes.dart

@@ -28,6 +28,7 @@
 // from the flutter/website PR, which has a GitHub action that automatically
 // stages commits to firebase. Example:
 // https://flutter-docs-prod--pr12652-devtools-release-notes-2-52-3bbb8c0u.web.app/tools/devtools/release-notes/release-notes-2.52.0.md.
+// ignore: unused-code, debug-only feature.
 String? _debugReleaseNotesUrl;
 
 const releaseNotesKey = Key('release_notes');

diff --git a/packages/devtools_app/lib/src/framework/scaffold/status_line.dart b/packages/devtools_app/lib/src/framework/scaffold/status_line.dart
index 16133d3..54e78dc 100644
--- a/packages/devtools_app/lib/src/framework/scaffold/status_line.dart
+++ b/packages/devtools_app/lib/src/framework/scaffold/status_line.dart

@@ -37,8 +37,6 @@
   /// Whether to highlight the footer when DevTools is connected to an app.
   final bool highlightForConnection;
 
-  static const deviceInfoTooltip = 'Device Info';
-
   /// The padding around the footer in the DevTools UI.
   EdgeInsets get padding => const EdgeInsets.symmetric(
     horizontal: defaultSpacing,