- Address review comments from https://codereview.chromium.org/474913004/

runtime/vm/thread_pool_test.cc

 // Copyright (c) 2012, 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.
 
 #include "vm/os.h"
 #include "vm/lockers.h"
 #include "vm/thread_pool.h"
 #include "vm/unit_test.h"
 
 namespace dart {
@@ skipping 17 matching lines @@
   ThreadPool thread_pool;
 }
 
 
 class TestTask : public ThreadPool::Task {
  public:
   TestTask(Monitor* sync, bool* done)
       : sync_(sync), done_(done) {
   }
 
-  void Run() {
+  virtual void Run() {
     MonitorLocker ml(sync_);
     *done_ = true;
     ml.Notify();
   }
 
  private:
   Monitor* sync_;
   bool* done_;
 };
 
@@ skipping 36 matching lines @@
   }
 }
 
 
 class SleepTask : public ThreadPool::Task {
  public:
   explicit SleepTask(int millis)
       : millis_(millis) {
   }
 
-  void Run() {
+  virtual void Run() {
     OS::Sleep(millis_);
   }
 
  private:
   int millis_;
 };
 
 
 UNIT_TEST_CASE(ThreadPool_WorkerShutdown) {
   Monitor exit_sync;
@@ skipping 53 matching lines @@
   FLAG_worker_timeout_millis = saved_timeout;
 }
 
 
 class SpawnTask : public ThreadPool::Task {
  public:
   SpawnTask(ThreadPool* pool, Monitor* sync, int todo, int total, int* done)
       : pool_(pool), sync_(sync), todo_(todo), total_(total), done_(done) {
   }
 
-  void Run() {
+  virtual void Run() {
     todo_--;  // Subtract one for current task.
     int child_todo = todo_ / 2;
 
     // Spawn 0-2 children.
     if (todo_ > 0) {
       pool_->Run(
           new SpawnTask(pool_, sync_, todo_ - child_todo, total_, done_));
     }
     if (todo_ > 1) {
       pool_->Run(
@@ skipping 29 matching lines @@
     MonitorLocker ml(&sync);
     while (done < kTotalTasks) {
       ml.Wait();
     }
   }
   EXPECT_EQ(kTotalTasks, done);
 }
 
 
 }  // namespace dart