refactor app.* daemon events (#6679)

packages/flutter_tools/lib/src/commands/daemon.dart

@@ -361,16 +361,25 @@ class AppDomain extends Domain {
         _sendAppEvent(app, 'debugPort', params);
       });
     }
+    Completer<Null> appStartedCompleter = new Completer<Null>();
+    appStartedCompleter.future.then((_) {
+      _sendAppEvent(app, 'started');
+    });
 
-    app._runInZone(this, () {
-      runner.run(connectionInfoCompleter: connectionInfoCompleter, route: route).then((_) {
+    app._runInZone(this, () async {
+      try {
+        await runner.run(
+          connectionInfoCompleter: connectionInfoCompleter,
+          appStartedCompleter: appStartedCompleter,
+          route: route,
+        );
         _sendAppEvent(app, 'stop');
-      }).catchError((dynamic error) {
-        _sendAppEvent(app, 'stop', <String, dynamic>{ 'error' : error.toString() });
-      }).whenComplete(() {
+      } catch (error) {
+        _sendAppEvent(app, 'stop', <String, dynamic>{'error': error.toString()});
+      } finally {
         Directory.current = cwd;
         _apps.remove(app);
-      });
+      }
     });
 
     return app;

packages/flutter_tools/lib/src/hot.dart

@@ -139,6 +139,7 @@ class HotRunner extends ResidentRunner {
   @override
   Future<int> run({
     Completer<DebugConnectionInfo> connectionInfoCompleter,
+    Completer<Null> appStartedCompleter,
     String route,
     bool shouldBuild: true
   }) {
@@ -146,6 +147,7 @@ class HotRunner extends ResidentRunner {
     return Chain.capture(() {
       return _run(
         connectionInfoCompleter: connectionInfoCompleter,
+        appStartedCompleter: appStartedCompleter,
         route: route,
         shouldBuild: shouldBuild
       );
@@ -173,6 +175,7 @@ class HotRunner extends ResidentRunner {
 
   Future<int> _run({
     Completer<DebugConnectionInfo> connectionInfoCompleter,
+    Completer<Null> appStartedCompleter,
     String route,
     bool shouldBuild: true
   }) async {
@@ -304,6 +307,12 @@ class HotRunner extends ResidentRunner {
 
     registerSignalHandlers();
 
+    printTrace('Finishing file synchronization');
+    // Finish the file sync now.
+    await _updateDevFS();
+
+    appStartedCompleter?.complete();
+
     if (benchmarkMode) {
       // We are running in benchmark mode.
       printStatus('Running in benchmark mode.');

packages/flutter_tools/lib/src/resident_runner.dart

@@ -40,6 +40,7 @@ abstract class ResidentRunner {
   /// Start the app and keep the process running during its lifetime.
   Future<int> run({
     Completer<DebugConnectionInfo> connectionInfoCompleter,
+    Completer<Null> appStartedCompleter,
     String route,
     bool shouldBuild: true
   });

packages/flutter_tools/lib/src/run.dart

@@ -45,6 +45,7 @@ class RunAndStayResident extends ResidentRunner {
   @override
   Future<int> run({
     Completer<DebugConnectionInfo> connectionInfoCompleter,
+    Completer<Null> appStartedCompleter,
     String route,
     bool shouldBuild: true
   }) {
@@ -55,6 +56,7 @@ class RunAndStayResident extends ResidentRunner {
         traceStartup: traceStartup,
         benchmark: benchmark,
         connectionInfoCompleter: connectionInfoCompleter,
+        appStartedCompleter: appStartedCompleter,
         route: route,
         shouldBuild: shouldBuild
       );
@@ -101,6 +103,7 @@ class RunAndStayResident extends ResidentRunner {
     bool traceStartup: false,
     bool benchmark: false,
     Completer<DebugConnectionInfo> connectionInfoCompleter,
+    Completer<Null> appStartedCompleter,
     String route,
     bool shouldBuild: true
   }) async {
@@ -185,8 +188,8 @@ class RunAndStayResident extends ResidentRunner {
 
     startTime.stop();
 
-    if (connectionInfoCompleter != null && _result.hasObservatory)
-      connectionInfoCompleter.complete(new DebugConnectionInfo(_result.observatoryPort));
+    if (_result.hasObservatory)
+      connectionInfoCompleter?.complete(new DebugConnectionInfo(_result.observatoryPort));
 
     // Connect to observatory.
     if (debuggingOptions.debuggingEnabled) {
@@ -218,6 +221,8 @@ class RunAndStayResident extends ResidentRunner {
       registerSignalHandlers();
     }
 
+    appStartedCompleter?.complete();
+
     if (benchmark) {
       await new Future<Null>.delayed(new Duration(seconds: 4));