Use cammelCase for all service extension variables

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 61 matching lines @@
   (Isolate isolate) async {
     await isolate.invokeRpcNoUpgrade('__setup', {});
     try {
       var result = await isolate.invokeRpcNoUpgrade('__getOpenFiles', {});
       expect(result['type'], equals('_openfiles'));
 
       expect(result['data'].length, equals(2));
       var writing = await isolate.invokeRpcNoUpgrade(
            '__getFileByID', { 'id' : result['data'][0]['id'] });
 
-      expect(writing['total_read'], equals(0));
-      expect(writing['read_count'], equals(0));
-      expect(writing['write_count'], equals(3));
-      expect(writing['total_written'], equals(3));
-      expect(writing['last_write'], greaterThan(0));
-      expect(writing['last_read'], equals(0));
+      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'] });
 
-      expect(reading['total_read'], equals(5));
-      expect(reading['read_count'], equals(5));
-      expect(reading['write_count'], equals(0));
-      expect(reading['total_written'], equals(0));
-      expect(reading['last_write'], equals(0));
-      expect(reading['last_read'], greaterThan(0));
+      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', {});
     }
   },
 ];
 
 main(args) async => runIsolateTests(args, fileTests, testeeBefore:setupFiles);