Fix an issue calculating analysis server cpu usage.

pkg/analysis_server/test/src/utilities/profiling_test.dart

 // Copyright (c) 2017, 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:io';
 
 import 'package:analysis_server/src/utilities/profiling.dart';
 import 'package:test/test.dart';
 
 main() {
   group('ProcessProfiler', () {
     // Skip on windows.
     if (Platform.isWindows) {
       return;
     }
 
     test('getProfilerForPlatform', () async {
       expect(ProcessProfiler.getProfilerForPlatform(), isNotNull);
     });
 
-    // TODO: https://github.com/dart-lang/sdk/issues/29815
-//    test('getProcessUsage', () async {
-//      ProcessProfiler profiler = ProcessProfiler.getProfilerForPlatform();
-//      UsageInfo info = await profiler.getProcessUsage(pid);
-//
-//      expect(info, isNotNull);
-//      expect(info.cpuPercentage, greaterThanOrEqualTo(0.0));
-//      expect(info.memoryKB, greaterThanOrEqualTo(0));
-//    });
+    test('getProcessUsage', () async {
+      ProcessProfiler profiler = ProcessProfiler.getProfilerForPlatform();
+      UsageInfo info = await profiler.getProcessUsage(pid);
+
+      expect(info, isNotNull);
+      expect(info.cpuPercentage, greaterThanOrEqualTo(0.0));
+      expect(info.memoryKB, greaterThanOrEqualTo(0));
+    });
   });
 }