Move _FileSystemWatcher to IO patch since it extends NativeFieldWrapperClass1.

sdk/lib/io/file_system_entity.dart

Index: sdk/lib/io/file_system_entity.dart
diff --git a/sdk/lib/io/file_system_entity.dart b/sdk/lib/io/file_system_entity.dart
index a00cb03229638eba8ab8c6330e0ec29cb9ee6692..8d86fe8f5d0f06b47fa57023ae309b32ffe06e37 100644
--- a/sdk/lib/io/file_system_entity.dart
+++ b/sdk/lib/io/file_system_entity.dart
@@ -420,7 +420,7 @@ abstract class FileSystemEntity {
 
   static _throwIfError(Object result, String msg, [String path]) {
     if (result is OSError) {
-      throw new FileException(msg, result, path);
+      throw new FileException(msg, path, result);
     } else if (result is ArgumentError) {
       throw result;
     }
@@ -535,97 +535,8 @@ class FileSystemMoveEvent extends FileSystemEvent {
 }
 
 
-class _FileSystemWatcher extends NativeFieldWrapperClass1 {
-  final String _path;
-  final int _events;
-  final bool _recursive;
+abstract class _FileSystemWatcher {
+  external factory _FileSystemWatcher(String path, int events, bool recursive);
 
-  StreamController _controller;
-  StreamSubscription _subscription;
-
-  _FileSystemWatcher(this._path, this._events, this._recursive) {
-    _controller = new StreamController(onListen: _listen, onCancel: _cancel);
-  }
-
-  void _listen() {
-    int socketId;
-    try {
-      socketId = _watchPath(_path, _events, identical(true, _recursive));
-    } catch (e) {
-      throw new FileException(
-          "Failed to watch path",
-          _path,
-          e);
-    }
-    var socket = new _RawSocket(new _NativeSocket.watch(socketId));
-    _subscription = socket.expand((event) {
-      var events = [];
-      var pair = {};
-      if (event == RawSocketEvent.READ) {
-        String getPath(event) {
-          var path = _path;
-          if (event[2] != null) {
-            path += Platform.pathSeparator;
-            path += event[2];
-          }
-          return path;
-        }
-        while (socket.available() > 0) {
-          for (var event in _readEvents()) {
-            if (event == null) continue;
-            var path = getPath(event);
-            if ((event[0] & FileSystemEvent.CREATE) != 0) {
-              events.add(new FileSystemCreateEvent._(path));
-            }
-            if ((event[0] & FileSystemEvent.MODIFY) != 0) {
-              events.add(new FileSystemModifyEvent._(path, true));
-            }
-            if ((event[0] & FileSystemEvent._MODIFY_ATTRIBUTES) != 0) {
-              events.add(new FileSystemModifyEvent._(path, false));
-            }
-            if ((event[0] & FileSystemEvent.MOVE) != 0) {
-              int link = event[1];
-              if (link > 0) {
-                if (pair.containsKey(link)) {
-                  events.add(
-                      new FileSystemMoveEvent._(getPath(pair[link]), path));
-                  pair.remove(link);
-                } else {
-                  pair[link] = event;
-                }
-              } else {
-                events.add(new FileSystemMoveEvent._(path, null));
-              }
-            }
-            if ((event[0] & FileSystemEvent.DELETE) != 0) {
-              events.add(new FileSystemDeleteEvent._(path));
-            }
-          }
-        }
-        for (var event in pair.values) {
-          events.add(new FileSystemMoveEvent._(getPath(event), null));
-        }
-      } else if (event == RawSocketEvent.CLOSED) {
-      } else if (event == RawSocketEvent.READ_CLOSED) {
-      } else {
-        assert(false);
-      }
-      return events;
-    })
-    .where((event) => (event.type & _events) != 0)
-    .listen(_controller.add, onDone: _cancel);
-  }
-
-  void _cancel() {
-    _unwatchPath();
-    if (_subscription != null) {
-      _subscription.cancel();
-    }
-  }
-
-  Stream<FileSystemEvent> get stream => _controller.stream;
-
-  external int _watchPath(String path, int events, bool recursive);
-  external void _unwatchPath();
-  external List _readEvents();
+  Stream<FileSystemEvent> get stream;
 }