TaskScheduler: Remove OnMainExit from SchedulerWorkerThread::Delegate.

base/task_scheduler/scheduler_worker_thread_unittest.cc

Index: base/task_scheduler/scheduler_worker_thread_unittest.cc
diff --git a/base/task_scheduler/scheduler_worker_thread_unittest.cc b/base/task_scheduler/scheduler_worker_thread_unittest.cc
index f3512a8da58baa266eeeb402ccf3125aeae17afc..541d1bc0800f315eea99b72ac7b60d7b141d6b2a 100644
--- a/base/task_scheduler/scheduler_worker_thread_unittest.cc
+++ b/base/task_scheduler/scheduler_worker_thread_unittest.cc
@@ -42,15 +42,7 @@ class TaskSchedulerWorkerThreadTest : public testing::TestWithParam<size_t>,
   }
 
   void TearDown() override {
-    {
-      AutoSchedulerLock auto_lock(lock_);
-      EXPECT_FALSE(main_exit_called_);
-    }
-
     worker_thread_->JoinForTesting();
-
-    AutoSchedulerLock auto_lock(lock_);
-    EXPECT_TRUE(main_exit_called_);
   }
 
   size_t TasksPerSequence() const { return GetParam(); }
@@ -100,12 +92,6 @@ class TaskSchedulerWorkerThreadTest : public testing::TestWithParam<size_t>,
     main_entry_called_.Signal();
   }
 
-  void OnMainExit() override {
-    AutoSchedulerLock auto_lock(lock_);
-    EXPECT_FALSE(main_exit_called_);
-    main_exit_called_ = true;
-  }
-
   scoped_refptr<Sequence> GetWork(
       SchedulerWorkerThread* worker_thread) override {
     EXPECT_EQ(worker_thread_.get(), worker_thread);
@@ -180,9 +166,6 @@ class TaskSchedulerWorkerThreadTest : public testing::TestWithParam<size_t>,
   // Signaled once OnMainEntry() has been called.
   WaitableEvent main_entry_called_;
 
-  // True once OnMainExit() has been called.
-  bool main_exit_called_ = false;
-
   // Number of Sequences that should be created by GetWork(). When this
   // is 0, GetWork() returns nullptr.
   size_t num_sequences_to_create_ = 0;