Generalize devtools events to support multiple screens

Author: Anna Gringauze

dwds/lib/src/dwds_vm_client.dart

@@ -157,12 +157,16 @@ class DwdsVmClient {
 
     client.registerServiceCallback('ext.dwds.sendEvent', (event) async {
       var type = event['type'] as String;
+      var payload = event['payload'] as Map<String, dynamic>;
       switch (type) {
-        case 'DevtoolsReady':
+        case 'DevtoolsEvent':
           {
-            emitEvent(DwdsEvent.debuggerReady(DateTime.now()
-                .difference(dwdsStats.debuggerStart)
-                .inMilliseconds));
+            var screen = payload == null ? null : payload['screen'];
+            if (screen == 'debugger' && dwdsStats.isFirstDebuggerReady()) {
+              emitEvent(DwdsEvent.debuggerReady(DateTime.now()
+                  .difference(dwdsStats.debuggerStart)
+                  .inMilliseconds));
+            }
           }
       }
       return {'result': Success().toJson()};

dwds/test/events_test.dart

@@ -88,9 +88,7 @@ void main() {
     await events;
   });
 
-  test(
-      'can receive DevtoolsReady event and emit DEBUGGER_READY '
-      'event through service extension', () async {
+  test('can receive DevtoolsEvent and emit DEBUGGER_READY event', () async {
     var events = expectLater(
         context.testServer.dwds.events,
         emitsThrough(predicate((DwdsEvent event) =>
@@ -99,8 +97,8 @@ void main() {
 
     var response = await context.debugConnection.vmService
         .callServiceExtension('ext.dwds.sendEvent', args: {
-      'type': 'DevtoolsReady',
-      'payload': {},
+      'type': 'DevtoolsEvent',
+      'payload': {'screen': 'debugger'},
     });
     expect(response.type, 'Success');
     await events;