Worker: Introduce per-global-scope task scheduler

third_party/WebKit/Source/platform/scheduler/child/webthread_impl_for_worker_scheduler.h

Index: third_party/WebKit/Source/platform/scheduler/child/webthread_impl_for_worker_scheduler.h
diff --git a/third_party/WebKit/Source/platform/scheduler/child/webthread_impl_for_worker_scheduler.h b/third_party/WebKit/Source/platform/scheduler/child/webthread_impl_for_worker_scheduler.h
index 21107a57279ac84cc159b79c21841cc69f4f09eb..47c4e3e439a8691f65e6259d8f5b3f3d3861fc92 100644
--- a/third_party/WebKit/Source/platform/scheduler/child/webthread_impl_for_worker_scheduler.h
+++ b/third_party/WebKit/Source/platform/scheduler/child/webthread_impl_for_worker_scheduler.h
@@ -48,8 +48,15 @@ class BLINK_PLATFORM_EXPORT WebThreadImplForWorkerScheduler
   // base::MessageLoop::DestructionObserver implementation.
   void WillDestroyCurrentMessageLoop() override;
 
+  scheduler::WorkerScheduler* GetWorkerScheduler() {
+    return worker_scheduler_.get();

[haraken, 2017/04/13 07:03:36]

It looks strange that:

- webthread_impl_for_worker_scheduler owns the scheduler by std::unique_ptr.

- the caller site also owns the scheduler by creating another std::unique_ptr by
calling MakeUnique(GetWorkerScheduler()).

Who should own the scheduler?

[nhiroki, 2017/04/13 08:23:50]

That MakeUnique creates Worker*GlobalScope*Scheduler, and it does NOT own the
passed WorkerScheduler.
- WebThreadImplForWorkerScheduler owns WorkerScheduler
    (per-thread object owns per-thread scheduler).
- WorkerThread owns WorkerGlobalScopeScheduler
    (per-global-scope object the per-global-scope scheduler)

+  }
+
  protected:
   base::Thread* GetThread() const { return thread_.get(); }
+  SchedulerTqmDelegate* task_runner_delegate() const {
+    return task_runner_delegate_.get();
+  }
 
  private:
   virtual std::unique_ptr<scheduler::WorkerScheduler> CreateWorkerScheduler();