Revert of [scheduler] Change TaskQueue observer call mechanism.

third_party/WebKit/Source/platform/scheduler/base/task_queue_impl.h

Index: third_party/WebKit/Source/platform/scheduler/base/task_queue_impl.h
diff --git a/third_party/WebKit/Source/platform/scheduler/base/task_queue_impl.h b/third_party/WebKit/Source/platform/scheduler/base/task_queue_impl.h
index fc20922acf9f2f25d30d021e42658bce175fb55a..dc36b1c12446eed6579e10f9a21292c8b21031a4 100644
--- a/third_party/WebKit/Source/platform/scheduler/base/task_queue_impl.h
+++ b/third_party/WebKit/Source/platform/scheduler/base/task_queue_impl.h
@@ -142,7 +142,7 @@
   bool IsQueueEnabled() const override;
   bool IsEmpty() const override;
   size_t GetNumberOfPendingTasks() const override;
-  bool HasTaskToRunImmediately() const override;
+  bool HasPendingImmediateWork() const override;
   base::Optional<base::TimeTicks> GetNextScheduledWakeUp() override;
   void SetQueuePriority(QueuePriority priority) override;
   QueuePriority GetQueuePriority() const override;
@@ -177,18 +177,6 @@
   void NotifyWillProcessTask(const base::PendingTask& pending_task);
   void NotifyDidProcessTask(const base::PendingTask& pending_task);
 
-  // Called by TimeDomain when the wake-up for this queue has changed.
-  // There is only one wake-up, new wake-up cancels any previous wake-ups.
-  // If |scheduled_time_domain_wake_up| is base::nullopt then the wake-up
-  // has been cancelled.
-  // Must be called from the main thread.
-  void SetScheduledTimeDomainWakeUp(
-      base::Optional<base::TimeTicks> scheduled_time_domain_wake_up);
-
-  // Check for available tasks in immediate work queues.
-  // Used to check if we need to generate notifications about delayed work.
-  bool HasPendingImmediateWork();
-
   WorkQueue* delayed_work_queue() {
     return main_thread_only().delayed_work_queue.get();
   }
@@ -214,8 +202,14 @@
   // any. Must be called from the main thread.
   base::Optional<DelayedWakeUp> WakeUpForDelayedWork(LazyNow* lazy_now);
 
-  base::Optional<base::TimeTicks> scheduled_time_domain_wake_up() const {
+  base::TimeTicks scheduled_time_domain_wake_up() const {
     return main_thread_only().scheduled_time_domain_wake_up;
+  }
+
+  void set_scheduled_time_domain_wake_up(
+      base::TimeTicks scheduled_time_domain_wake_up) {
+    main_thread_only().scheduled_time_domain_wake_up =
+        scheduled_time_domain_wake_up;
   }
 
   HeapHandle heap_handle() const { return main_thread_only().heap_handle; }
@@ -291,7 +285,7 @@
     int voter_refcount;
     base::trace_event::BlameContext* blame_context;  // Not owned.
     EnqueueOrder current_fence;
-    base::Optional<base::TimeTicks> scheduled_time_domain_wake_up;
+    base::TimeTicks scheduled_time_domain_wake_up;
   };
 
   ~TaskQueueImpl() override;
@@ -353,6 +347,8 @@
   // Schedules delayed work on time domain and calls the observer.
   void ScheduleDelayedWorkInTimeDomain(base::TimeTicks now);
 
+  void NotifyWakeUpChangedOnMainThread(base::TimeTicks wake_up);
+
   const base::PlatformThreadId thread_id_;
 
   mutable base::Lock any_thread_lock_;