dart:developer service extension fixes

runtime/observatory/tests/service/file_service_test.dart

 // Copyright (c) 2015, 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.
 
 import 'dart:async';
 import 'dart:convert';
 import 'dart:developer';
 import 'dart:io' as io;
 import 'package:observatory/service_io.dart';
 import 'package:unittest/unittest.dart';
@@ skipping 46 matching lines @@
       var result = await readTemp.readAsString();
       expect(result, equals('foobar'));
 
     } catch (e) {
       closeDown();
       throw e;
     }
     var result = JSON.encode({'type' : 'foobar'});
     return new Future.value(new ServiceExtensionResponse.result(result));
   }
-  registerExtension('__cleanup', cleanup);
-  registerExtension('__setup', setup);
+  registerExtension('ext.dart.io.cleanup', cleanup);
+  registerExtension('ext.dart.io.setup', setup);
 }
 
 var fileTests = [
   (Isolate isolate) async {
-    await isolate.invokeRpcNoUpgrade('__setup', {});
+    await isolate.invokeRpcNoUpgrade('ext.dart.io.setup', {});
     try {
-      var result = await isolate.invokeRpcNoUpgrade('__getOpenFiles', {});
+      var result =
+          await isolate.invokeRpcNoUpgrade('ext.dart.io.getOpenFiles', {});
       expect(result['type'], equals('_openfiles'));
 
       expect(result['data'].length, equals(2));
       var writing = await isolate.invokeRpcNoUpgrade(
-           '__getFileByID', { 'id' : result['data'][0]['id'] });
+           'ext.dart.io.getFileByID', { 'id' : result['data'][0]['id'] });
 
       expect(writing['totalRead'], equals(0));
       expect(writing['readCount'], equals(0));
       expect(writing['writeCount'], equals(3));
       expect(writing['totalWritten'], equals(3));
       expect(writing['lastWrite'], greaterThan(0));
       expect(writing['lastRead'], equals(0));
 
       var reading = await isolate.invokeRpcNoUpgrade(
-          '__getFileByID', { 'id' : result['data'][1]['id'] });
+          'ext.dart.io.getFileByID', { 'id' : result['data'][1]['id'] });
 
       expect(reading['totalRead'], equals(5));
       expect(reading['readCount'], equals(5));
       expect(reading['writeCount'], equals(0));
       expect(reading['totalWritten'], equals(0));
       expect(reading['lastWrite'], equals(0));
       expect(reading['lastRead'], greaterThan(0));
 
     } finally {
-      await isolate.invokeRpcNoUpgrade('__cleanup', {});
+      await isolate.invokeRpcNoUpgrade('ext.dart.io.cleanup', {});
     }
   },
 ];
 
 main(args) async => runIsolateTests(args, fileTests, testeeBefore:setupFiles);