Add initial Random Access File information to Observatory

sdk/lib/io/file_impl.dart

Index: sdk/lib/io/file_impl.dart
diff --git a/sdk/lib/io/file_impl.dart b/sdk/lib/io/file_impl.dart
index 5b4cddb0bd2b3f3490e00372834ba0ce5cb43581..d5e4cfc2950e1f203fa63a091a43800537f87a78 100644
--- a/sdk/lib/io/file_impl.dart
+++ b/sdk/lib/io/file_impl.dart
@@ -556,18 +556,51 @@ class _File extends FileSystemEntity implements File {
 }
 
 
-class _RandomAccessFile implements RandomAccessFile {
+class _RandomAccessFile
+    extends Object with _ServiceObject
+    implements RandomAccessFile {
+  // Use default Map so we keep order.
+  static Map<int, _RandomAccessFile> _files = new Map<int, _RandomAccessFile>();
+
   final String path;
   int _id;
   bool _asyncDispatched = false;
   SendPort _fileService;
 
-  _RandomAccessFile(this._id, this.path);
+
+  _RandomAccessFile(this._id, this.path) {
+    _files[_serviceId] = this;
+  }
+
+  String get _serviceTypePath => 'io/file/randomaccessfiles';
+  String get _serviceTypeName => 'RandomAccessFile';
+
+  Map _toJSON(bool ref) {
+    var r = {
+      'id': _servicePath,
+      'type': _serviceType(ref),
+      'name': '$path',
+      'user_name': '$path',
+    };
+    if (ref) {
+      return r;
+    }
+    r['asyncDispatched'] = _asyncDispatched;
+    r['fd'] = _id;
+    return r;
+  }
+
+  void _maybePerformCleanup() {
+    if (closed) {
+      _files.remove(_serviceId);
+    }
+  }
 
   Future<RandomAccessFile> close() {
     return _dispatch(_FILE_CLOSE, [_id], markClosed: true).then((result) {
       if (result != -1) {
         _id = result;
+        _maybePerformCleanup();
         return this;
       } else {
         throw new FileSystemException("Cannot close file", path);
@@ -584,6 +617,7 @@ class _RandomAccessFile implements RandomAccessFile {
       throw new FileSystemException("Cannot close file", path);
     }
     _id = id;
+    _maybePerformCleanup();
   }
 
   Future<int> readByte() {