Reorganize barback's source files.

pkg/barback/lib/src/graph/transform_node.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-library barback.transform_node;
+library barback.graph.transform_node;
 
 import 'dart:async';
 
-import 'asset.dart';
-import 'asset_id.dart';
-import 'asset_node.dart';
-import 'declaring_transform.dart';
-import 'declaring_transformer.dart';
-import 'errors.dart';
-import 'lazy_transformer.dart';
-import 'log.dart';
+import '../asset/asset.dart';
+import '../asset/asset_id.dart';
+import '../asset/asset_node.dart';
+import '../errors.dart';
+import '../log.dart';
+import '../transformer/declaring_transform.dart';
+import '../transformer/declaring_transformer.dart';
+import '../transformer/lazy_transformer.dart';
+import '../transformer/transform.dart';
+import '../transformer/transformer.dart';
+import '../utils.dart';
 import 'node_status.dart';
 import 'node_streams.dart';
 import 'phase.dart';
-import 'transform.dart';
-import 'transformer.dart';
-import 'utils.dart';
 
 /// Describes a transform on a set of assets and its relationship to the build
 /// dependency graph.
 ///
 /// Keeps track of whether it's dirty and needs to be run and which assets it
 /// depends on.
 class TransformNode {
   /// The [Phase] that this transform runs in.
   final Phase phase;
 
@@ skipping 493 matching lines @@
   /// If an input changes, this will transition to [DECLARED] if the transform
   /// is deferred and [APPLYING] otherwise.
   static final APPLIED = const _State._("applied");
 
   final String name;
 
   const _State._(this.name);
 
   String toString() => name;
 }