[flutter_tool] Use product runner in Fuchsia release build (#33282)

packages/flutter_tools/lib/src/fuchsia/fuchsia_build.dart

@@ -5,10 +5,12 @@
 import 'package:meta/meta.dart';
 
 import '../asset.dart';
+import '../base/common.dart';
 import '../base/file_system.dart';
 import '../base/io.dart';
 import '../build_info.dart';
 import '../bundle.dart';
+import '../convert.dart';
 import '../devfs.dart';
 import '../project.dart';
 
@@ -67,6 +69,31 @@ Future<void> _buildAssets(
   await outFile.close();
 }
 
+void _rewriteCmx(BuildMode mode, File src, File dst) {
+  final Map<String, dynamic> cmx = json.decode(src.readAsStringSync());
+  // If the app author has already specified the runner in the cmx file, then
+  // do not override it with something else.
+  if (cmx.containsKey('runner')) {
+    dst.writeAsStringSync(json.encode(cmx));
+    return;
+  }
+  String runner;
+  switch (mode) {
+    case BuildMode.debug:
+    case BuildMode.profile:
+      runner = 'flutter_jit_runner';
+      break;
+    case BuildMode.release:
+      runner = 'flutter_jit_product_runner';
+      break;
+    default:
+      throwToolExit('Fuchsia does not support build mode "$mode"');
+      break;
+  }
+  cmx['runner'] = 'fuchsia-pkg://fuchsia.com/$runner#meta/$runner.cmx';
+  dst.writeAsStringSync(json.encode(cmx));
+}
+
 // TODO(zra): Allow supplying a signing key.
 Future<void> _buildPackage(
     FuchsiaProject fuchsiaProject,
@@ -85,13 +112,17 @@ Future<void> _buildPackage(
     pkg.createSync(recursive: true);
   }
 
+  final File srcCmx =
+      fs.file(fs.path.join(fuchsiaProject.meta.path, '$appName.cmx'));
+  final File dstCmx = fs.file(fs.path.join(outDir, '$appName.cmx'));
+  _rewriteCmx(buildInfo.mode, srcCmx, dstCmx);
+
   // Concatenate dilpmanifest and pkgassets into package_manifest.
   final File manifestFile = fs.file(packageManifest);
   manifestFile.writeAsStringSync(fs.file(dilpmanifest).readAsStringSync());
   manifestFile.writeAsStringSync(fs.file(pkgassets).readAsStringSync(),
       mode: FileMode.append);
-  manifestFile.writeAsStringSync(
-      'meta/$appName.cmx=${fuchsiaProject.meta.path}/$appName.cmx\n',
+  manifestFile.writeAsStringSync('meta/$appName.cmx=${dstCmx.path}\n',
       mode: FileMode.append);
   manifestFile.writeAsStringSync('meta/package=$pkgDir/meta/package\n',
       mode: FileMode.append);

packages/flutter_tools/test/commands/build_fuchsia_test.dart

@@ -84,7 +84,8 @@ void main() {
       const String appName = 'app_name';
       fs
           .file(fs.path.join('fuchsia', 'meta', '$appName.cmx'))
-          .createSync(recursive: true);
+          ..createSync(recursive: true)
+          ..writeAsStringSync('{}');
       fs.file('.packages').createSync();
       final File pubspecFile = fs.file('pubspec.yaml')..createSync();
       pubspecFile.writeAsStringSync('name: $appName');
@@ -105,7 +106,8 @@ void main() {
       const String appName = 'app_name';
       fs
           .file(fs.path.join('fuchsia', 'meta', '$appName.cmx'))
-          .createSync(recursive: true);
+          ..createSync(recursive: true)
+          ..writeAsStringSync('{}');
       fs.file('.packages').createSync();
       fs.file(fs.path.join('lib', 'main.dart')).createSync(recursive: true);
       final File pubspecFile = fs.file('pubspec.yaml')..createSync();
@@ -127,7 +129,8 @@ void main() {
     const String appName = 'app_name';
     fs
         .file(fs.path.join('fuchsia', 'meta', '$appName.cmx'))
-        .createSync(recursive: true);
+        ..createSync(recursive: true)
+        ..writeAsStringSync('{}');
     fs.file('.packages').createSync();
     fs.file(fs.path.join('lib', 'main.dart')).createSync(recursive: true);
     final File pubspecFile = fs.file('pubspec.yaml')..createSync();

packages/flutter_tools/test/fuchsia/fuchsa_device_test.dart

@@ -434,7 +434,8 @@ void main() {
         app = FuchsiaApp.fromPrebuiltApp(far);
       } else {
         fs.file(fs.path.join('fuchsia', 'meta', '$appName.cmx'))
-          .createSync(recursive: true);
+          ..createSync(recursive: true)
+          ..writeAsStringSync('{}');
         fs.file('.packages').createSync();
         fs.file(fs.path.join('lib', 'main.dart')).createSync(recursive: true);
         app = BuildableFuchsiaApp(project: FlutterProject.current().fuchsia);