Add file watching to pub serve.

sdk/lib/_internal/pub/lib/src/pub_package_provider.dart

Index: sdk/lib/_internal/pub/lib/src/pub_package_provider.dart
diff --git a/sdk/lib/_internal/pub/lib/src/pub_package_provider.dart b/sdk/lib/_internal/pub/lib/src/pub_package_provider.dart
index b1c2821e17855a28ef2fbe4c7b9ef5162c7e1c11..0c4357196b9fba61453800d5b2b85fbbed2b611e 100644
--- a/sdk/lib/_internal/pub/lib/src/pub_package_provider.dart
+++ b/sdk/lib/_internal/pub/lib/src/pub_package_provider.dart
@@ -10,14 +10,10 @@ import 'package:barback/barback.dart';
 import 'package:path/path.dart' as path;
 
 import 'entrypoint.dart';
-import 'io.dart';
 
 /// An implementation of barback's [PackageProvider] interface so that barback
 /// can assets within pub packages.
 class PubPackageProvider implements PackageProvider {
-  /// The [Entrypoint] package being served.
-  final Entrypoint _entrypoint;
-
   /// Maps the names of all of the packages in [_entrypoint]'s transitive
   /// dependency graph to the local path of the directory for that package.
   final Map<String, String> _packageDirs;
@@ -30,7 +26,6 @@ class PubPackageProvider implements PackageProvider {
 
     // Cache package directories up front so we can have synchronous access
     // to them.
-    // TODO(rnystrom): Handle missing or out of date lockfile.
     var futures = [];
     entrypoint.loadLockFile().packages.forEach((name, package) {
       var source = entrypoint.cache.sources[package.source];
@@ -40,51 +35,16 @@ class PubPackageProvider implements PackageProvider {
     });
 
     return Future.wait(futures).then((_) {
-      return new PubPackageProvider._(entrypoint, packageDirs);
+      return new PubPackageProvider._(packageDirs);
     });
   }
 
-  PubPackageProvider._(this._entrypoint, this._packageDirs);
+  PubPackageProvider._(this._packageDirs);
 
   Iterable<String> get packages => _packageDirs.keys;
 
-  /// Lists all of the visible files in [package].
-  ///
-  /// This is the recursive contents of the "asset" and "lib" directories (if
-  /// present). If [package] is the entrypoint package, it also includes the
-  /// contents of "web".
-  List<AssetId> listAssets(String package) {
-    var files = <AssetId>[];
-
-    addFiles(String dirPath) {
-      var packageDir = _packageDirs[package];
-      var dir = path.join(packageDir, dirPath);
-      if (!dirExists(dir)) return;
-      for (var entry in listDir(dir, recursive: true)) {
-        // Ignore "packages" symlinks if there.
-        if (path.split(entry).contains("packages")) continue;
-
-        // Skip directories.
-        if (!fileExists(entry)) continue;
-
-        // AssetId paths use "/" on all platforms.
-        var relative = path.relative(entry, from: packageDir);
-        relative = path.toUri(relative).path;
-        files.add(new AssetId(package, relative));
-      }
-    }
-
-    // Expose the "asset" and "lib" directories.
-    addFiles("asset");
-    addFiles("lib");
-
-    // The entrypoint's "web" directory is also visible.
-    if (package == _entrypoint.root.name) {
-      addFiles("web");
-    }
-
-    return files;
-  }
+  /// Gets the root directory of [package].
+  String getPackageDir(String package) => _packageDirs[package];
 
   // TODO(rnystrom): Actually support transformers.
   Iterable<Iterable<Transformer>> getTransformers(String package) => [];