Use cammelCase for all service extension variables

runtime/observatory/tests/service/process_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 76 matching lines @@
       var all = await isolate.invokeRpcNoUpgrade('__getProcesses', {});
       expect(all['type'], equals('_startedprocesses'));
 
       expect(all['data'].length, equals(3));
 
       var first = await isolate.invokeRpcNoUpgrade(
           '__getProcessById', { 'id' : all['data'][0]['id'] });
       expect(first['name'], io.Platform.executable);
       expect(first['pid'], equals(setup['pids'][0]));
       expect(first['arguments'].contains('foobar'), isFalse);
-      expect(first['started_at'], greaterThan(0));
+      expect(first['startedAt'], greaterThan(0));
 
       var second = await isolate.invokeRpcNoUpgrade(
           '__getProcessById', { 'id' : all['data'][1]['id'] });
       expect(second['name'], io.Platform.executable);
       expect(second['pid'], equals(setup['pids'][1]));
       expect(second['arguments'].contains('foobar'), isTrue);
       expect(second['pid'] != first['pid'], isTrue);
-      expect(second['started_at'], greaterThan(0));
-      expect(second['started_at'], greaterThanOrEqualTo(first['started_at']));
+      expect(second['startedAt'], greaterThan(0));
+      expect(second['startedAt'], greaterThanOrEqualTo(first['startedAt']));
 
       var third = await isolate.invokeRpcNoUpgrade(
           '__getProcessById', { 'id' : all['data'][2]['id'] });
       expect(third['name'], io.Platform.executable);
       expect(third['pid'], equals(setup['pids'][2]));
       expect(third['pid'] != first['pid'], isTrue);
       expect(third['pid'] != second['pid'], isTrue);
-      expect(third['started_at'], greaterThanOrEqualTo(second['started_at']));
+      expect(third['startedAt'], greaterThanOrEqualTo(second['startedAt']));
 
       await isolate.invokeRpcNoUpgrade('__closeStdin', {});
       all = await isolate.invokeRpcNoUpgrade('__getProcesses', {});
       expect(all['type'], equals('_startedprocesses'));
       expect(all['data'].length, equals(2));
     } finally {
       await isolate.invokeRpcNoUpgrade('__cleanup', {});
     }
   },
 ];
 
 main(args) async => runIsolateTests(args, processTests,
                                     testeeBefore:setupProcesses);