Send a kPausePostRequest after restarting to notify clients to resume (#2441)

Author: elliette

Diff for: dwds/CHANGELOG.md

@@ -2,6 +2,7 @@
 
 - Fix bug where debugging clients are not aware of service extensions when connecting to a new web app. - [#2388](https://github.com/dart-lang/webdev/pull/2388)
 - Respect the value of `pause_isolates_on_start` during page-refreshes. - [#2431](https://github.com/dart-lang/webdev/pull/2431)
+- Fix issue where DAP clients wouldn't resume after a restart. - [#2441](https://github.com/dart-lang/webdev/pull/2441)
 
 ## 24.0.0
 

Diff for: dwds/lib/src/services/chrome_proxy_service.dart

@@ -99,6 +99,9 @@ class ChromeProxyService implements VmServiceInterface {
   /// This value can be updated at runtime via [setFlag].
   bool get pauseIsolatesOnStart => _pauseIsolatesOnStart;
 
+  /// Whether or not the connected app has a pending restart.
+  bool get hasPendingRestart => _resumeAfterRestartEventsController.hasListener;
+
   final _resumeAfterRestartEventsController =
       StreamController<String>.broadcast();
 
@@ -353,6 +356,20 @@ class ChromeProxyService implements VmServiceInterface {
       );
     }
 
+    // If the new isolate was created as part of a restart, send a
+    // kPausePostRequest event to notify client that the app is paused so that
+    // it can resume:
+    if (hasPendingRestart) {
+      _streamNotify(
+        'Debug',
+        Event(
+          kind: EventKind.kPausePostRequest,
+          timestamp: timestamp,
+          isolate: isolateRef,
+        ),
+      );
+    }
+
     // The service is considered initialized when the first isolate is created.
     if (!_initializedCompleter.isCompleted) _initializedCompleter.complete();
   }