Revert of [scheduler] Change TaskQueue observer call mechanism.

third_party/WebKit/Source/platform/scheduler/base/time_domain.cc

Index: third_party/WebKit/Source/platform/scheduler/base/time_domain.cc
diff --git a/third_party/WebKit/Source/platform/scheduler/base/time_domain.cc b/third_party/WebKit/Source/platform/scheduler/base/time_domain.cc
index 66b7bae655c7a1f31e62a7a199469a58f5a001e8..bdf885b5da186342be32f72947d9259b9edfdcdf 100644
--- a/third_party/WebKit/Source/platform/scheduler/base/time_domain.cc
+++ b/third_party/WebKit/Source/platform/scheduler/base/time_domain.cc
@@ -41,7 +41,7 @@
   // We only want to store a single wake-up per queue, so we need to remove any
   // previously registered wake up for |queue|.
   if (queue->heap_handle().IsValid()) {
-    DCHECK(queue->scheduled_time_domain_wake_up());
+    DCHECK_NE(queue->scheduled_time_domain_wake_up(), base::TimeTicks());
 
     // O(log n)
     delayed_wake_up_queue_.ChangeKey(queue->heap_handle(), {wake_up, queue});
@@ -50,7 +50,7 @@
     delayed_wake_up_queue_.insert({wake_up, queue});
   }
 
-  queue->SetScheduledTimeDomainWakeUp(wake_up.time);
+  queue->set_scheduled_time_domain_wake_up(wake_up.time);
 
   // If |queue| is the first wake-up then request the wake-up.
   if (delayed_wake_up_queue_.Min().queue == queue)
@@ -65,7 +65,7 @@
   if (!queue->heap_handle().IsValid())
     return;
 
-  DCHECK(queue->scheduled_time_domain_wake_up());
+  DCHECK_NE(queue->scheduled_time_domain_wake_up(), base::TimeTicks());
   DCHECK(!delayed_wake_up_queue_.empty());
   base::TimeTicks prev_first_wake_up =
       delayed_wake_up_queue_.Min().wake_up.time;
@@ -95,11 +95,11 @@
     if (next_wake_up) {
       // O(log n)
       delayed_wake_up_queue_.ReplaceMin({*next_wake_up, queue});
-      queue->SetScheduledTimeDomainWakeUp(next_wake_up->time);
+      queue->set_scheduled_time_domain_wake_up(next_wake_up->time);
     } else {
       // O(log n)
       delayed_wake_up_queue_.Pop();
-      DCHECK(!queue->scheduled_time_domain_wake_up());
+      DCHECK_EQ(queue->scheduled_time_domain_wake_up(), base::TimeTicks());
     }
   }
 }