add route information to Flutter.Navigation events (#34508)

* add route information to Flutter.Navigation events

* route can be null; re-work how we send route info to accomidate that

dev/devicelab/bin/tasks/service_extensions_test.dart

@@ -94,9 +94,16 @@ void main() {
       final Future<VMExtensionEvent> navigationFuture = navigationEvents.first;
       // This tap triggers a navigation event.
       device.tap(100, 200);
+
       final VMExtensionEvent navigationEvent = await navigationFuture;
-      // Validate that there are not any fields.
-      expect(navigationEvent.data.isEmpty);
+      // validate the fields
+      expect(navigationEvent.data['route'] is Map<dynamic, dynamic>);
+      final Map<dynamic, dynamic> route = navigationEvent.data['route'];
+      expect(route['description'] is String);
+      expect(route['settings'] is Map<dynamic, dynamic>);
+      final Map<dynamic, dynamic> settings = route['settings'];
+      expect(settings.containsKey('name'));
+      expect(settings['isInitialRoute'] is bool);
 
       run.stdin.write('q');
       final int result = await run.exitCode;

packages/flutter/lib/src/widgets/navigator.dart

@@ -3,6 +3,7 @@
 // found in the LICENSE file.
 
 import 'dart:async';
+import 'dart:convert';
 import 'dart:developer' as developer;
 
 import 'package:flutter/foundation.dart';
@@ -15,6 +16,7 @@ import 'focus_manager.dart';
 import 'focus_scope.dart';
 import 'framework.dart';
 import 'overlay.dart';
+import 'routes.dart';
 import 'ticker_provider.dart';
 
 // Examples can assume:
@@ -1760,18 +1762,46 @@ class NavigatorState extends State<Navigator> with TickerProviderStateMixin {
     for (NavigatorObserver observer in widget.observers)
       observer.didPush(route, oldRoute);
     assert(() { _debugLocked = false; return true; }());
-    _afterNavigation();
+    _afterNavigation(route);
     return route.popped;
   }
 
-  void _afterNavigation() {
+  void _afterNavigation<T>(Route<T> route) {
     if (!kReleaseMode) {
-      // This event is used by performance tools that show stats for the
-      // time interval since the last navigation event occurred ensuring that
-      // stats only reflect the current page.
-      // These tools do not need to know exactly what the new route is so no
-      // attempt is made to describe the current route as part of the event.
-      developer.postEvent('Flutter.Navigation', <String, dynamic>{});
+      // Among other uses, performance tools use this event to ensure that perf
+      // stats reflect the time interval since the last navigation event
+      // occurred, ensuring that stats only reflect the current page.
+
+      Map<String, dynamic> routeJsonable;
+      if (route != null) {
+        routeJsonable = <String, dynamic>{};
+
+        String description;
+        if (route is TransitionRoute<T>) {
+          final TransitionRoute<T> transitionRoute = route;
+          description = transitionRoute.debugLabel;
+        } else {
+          description = '$route';
+        }
+        routeJsonable['description'] = description;
+
+        final RouteSettings settings = route.settings;
+        final Map<String, dynamic> settingsJsonable = <String, dynamic> {
+          'name': settings.name,
+          'isInitialRoute': settings.isInitialRoute,
+        };
+        if (settings.arguments != null) {
+          settingsJsonable['arguments'] = jsonEncode(
+            settings.arguments,
+            toEncodable: (Object object) => '$object',
+          );
+        }
+        routeJsonable['settings'] = settingsJsonable;
+      }
+
+      developer.postEvent('Flutter.Navigation', <String, dynamic>{
+        'route': routeJsonable,
+      });
     }
     _cancelActivePointers();
   }
@@ -1825,7 +1855,7 @@ class NavigatorState extends State<Navigator> with TickerProviderStateMixin {
     for (NavigatorObserver observer in widget.observers)
       observer.didReplace(newRoute: newRoute, oldRoute: oldRoute);
     assert(() { _debugLocked = false; return true; }());
-    _afterNavigation();
+    _afterNavigation(newRoute);
     return newRoute.popped;
   }
 
@@ -1879,7 +1909,7 @@ class NavigatorState extends State<Navigator> with TickerProviderStateMixin {
         observer.didRemove(removedRoute, oldRoute);
     }
     assert(() { _debugLocked = false; return true; }());
-    _afterNavigation();
+    _afterNavigation(newRoute);
     return newRoute.popped;
   }
 
@@ -2032,7 +2062,7 @@ class NavigatorState extends State<Navigator> with TickerProviderStateMixin {
       assert(!debugPredictedWouldPop);
     }
     assert(() { _debugLocked = false; return true; }());
-    _afterNavigation();
+    _afterNavigation<dynamic>(route);
     return true;
   }
 
@@ -2074,7 +2104,7 @@ class NavigatorState extends State<Navigator> with TickerProviderStateMixin {
       observer.didRemove(route, previousRoute);
     route.dispose();
     assert(() { _debugLocked = false; return true; }());
-    _afterNavigation();
+    _afterNavigation<dynamic>(nextRoute);
   }
 
   /// Immediately remove a route from the navigator, and [Route.dispose] it. The