Duplicate assets under data/ to data/componentName (#20534)

packages/flutter_tools/bin/fuchsia_asset_builder.dart

@@ -22,6 +22,7 @@ const String _kOptionPackages = 'packages';
 const String _kOptionAsset = 'asset-dir';
 const String _kOptionManifest = 'manifest';
 const String _kOptionAssetManifestOut = 'asset-manifest-out';
+const String _kOptionComponentName = 'component-name';
 const List<String> _kRequiredOptions = <String>[
   _kOptionPackages,
   _kOptionAsset,
@@ -47,7 +48,8 @@ Future<Null> run(List<String> args) async {
     ..addOption(_kOptionAsset,
         help: 'The directory where to put temporary files')
     ..addOption(_kOptionManifest, help: 'The manifest file')
-    ..addOption(_kOptionAssetManifestOut);
+    ..addOption(_kOptionAssetManifestOut)
+    ..addOption(_kOptionComponentName);
   final ArgResults argResults = parser.parse(args);
   if (_kRequiredOptions
       .any((String option) => !argResults.options.contains(option))) {
@@ -77,10 +79,10 @@ Future<Null> run(List<String> args) async {
   await Future.wait(calls);
 
   final String outputMan = argResults[_kOptionAssetManifestOut];
-  await writeFuchsiaManifest(assets, argResults[_kOptionAsset], outputMan);
+  await writeFuchsiaManifest(assets, argResults[_kOptionAsset], outputMan, argResults[_kOptionComponentName]);
 }
 
-Future<Null> writeFuchsiaManifest(AssetBundle assets, String outputBase, String fileDest) async {
+Future<Null> writeFuchsiaManifest(AssetBundle assets, String outputBase, String fileDest, String componentName) async {
 
   final libfs.File destFile = libfs.fs.file(fileDest);
   await destFile.create(recursive: true);
@@ -88,6 +90,9 @@ Future<Null> writeFuchsiaManifest(AssetBundle assets, String outputBase, String
 
   for (String path in assets.entries.keys) {
     outFile.write('data/$path=$outputBase/$path\n');
+    if (componentName.isNotEmpty) {
+      outFile.write('data/$componentName/$path=$outputBase/$path\n');
+    }
   }
   await outFile.flush();
   await outFile.close();