[flutter_tool] Change the startup message for the "flutter daemon" command (#160444)

There have been some reports of the Flutter daemon not starting up
properly (for ex. flutter/flutter#143625), but
it turns out that when starting successfully, it just prints "Starting
device daemon..." and then nothing more. This is confusing and can lead
users to think other issues are because the daemon hasn't started
properly.

There's not a great hook to print that this "finished" starting up
(because it does async polling in the background), so I just updated the
message of the text and moved it to after the creation of the daemon.

Fixes flutter/flutter#143625

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we expect every widget to implement].
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above.
- [x] I updated/added relevant documentation (doc comments with `///`).
- [x] I added new tests to check the change I am making, or this PR is
[test-exempt].
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Fixes] where supported.
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---------

Co-authored-by: Andrew Kolos <andrewrkolos@gmail.com>

Author: DanTup

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

@@ -86,14 +86,14 @@ class DaemonCommand extends FlutterCommand {
       ).run();
       return FlutterCommandResult.success();
     }
-    globals.printStatus('Starting device daemon...');
     final Daemon daemon = Daemon(
       DaemonConnection(
         daemonStreams: DaemonStreams.fromStdio(globals.stdio, logger: globals.logger),
         logger: globals.logger,
       ),
       notifyingLogger: asLogger<NotifyingLogger>(globals.logger),
     );
+    globals.printStatus('Device daemon started.');
     final int code = await daemon.onExit;
     if (code != 0) {
       throwToolExit('Daemon exited with non-zero exit code: $code', exitCode: code);

packages/flutter_tools/test/integration.shard/daemon_mode_test.dart

@@ -27,6 +27,42 @@ void main() {
     daemonProcess.kill();
   });
 
+  testWithoutContext('startup events', () async {
+    final BasicProject project = BasicProject();
+    await project.setUpIn(tempDir);
+
+    const ProcessManager processManager = LocalProcessManager();
+    daemonProcess = await processManager.start(
+      <String>[flutterBin, ...getLocalEngineArguments(), '--show-test-device', 'daemon'],
+      workingDirectory: tempDir.path,
+    );
+
+    final StreamController<String> stdout = StreamController<String>.broadcast();
+    transformToLines(daemonProcess.stdout).listen((String line) => stdout.add(line));
+    final Stream<Map<String, Object?>> stream =
+        stdout.stream
+            .map<Map<String, Object?>?>(parseFlutterResponse)
+            .where((Map<String, Object?>? value) => value != null)
+            .cast<Map<String, Object?>>();
+
+    final [
+      Map<String, Object?> connectedEvent,
+      Map<String, Object?> logMessage,
+    ] = await Future.wait(<Future<Map<String, Object?>>>[
+      stream.firstWhere((Map<String, Object?> e) => e['event'] == 'daemon.connected'),
+      stream.firstWhere((Map<String, Object?> e) => e['event'] == 'daemon.logMessage'),
+    ]);
+
+    // Check the connected message has a version.
+    final Map<String, Object?> connectedParams = connectedEvent['params']! as Map<String, Object?>;
+    expect(connectedParams['version'], isNotNull);
+
+    // Check we got the startup message.
+    final Map<String, Object?> logParams = logMessage['params']! as Map<String, Object?>;
+    expect(logParams['level'], 'status');
+    expect(logParams['message'], 'Device daemon started.');
+  });
+
   testWithoutContext('device.getDevices', () async {
     final BasicProject project = BasicProject();
     await project.setUpIn(tempDir);