Revert of Worker: Introduce per-global-scope task scheduler

third_party/WebKit/Source/core/workers/WorkerEventQueue.cpp

Index: third_party/WebKit/Source/core/workers/WorkerEventQueue.cpp
diff --git a/third_party/WebKit/Source/core/workers/WorkerEventQueue.cpp b/third_party/WebKit/Source/core/workers/WorkerEventQueue.cpp
index e6a3c08f4ceaa151016d0773ad7bd54ee2af3dea..1c33fed8ef20fc79c6eb776c4b6ee5b057994dd5 100644
--- a/third_party/WebKit/Source/core/workers/WorkerEventQueue.cpp
+++ b/third_party/WebKit/Source/core/workers/WorkerEventQueue.cpp
@@ -26,7 +26,6 @@
 
 #include "core/workers/WorkerEventQueue.h"
 
-#include "core/dom/TaskRunnerHelper.h"
 #include "core/events/Event.h"
 #include "core/probe/CoreProbes.h"
 #include "core/workers/WorkerGlobalScope.h"
@@ -58,16 +57,10 @@
   probe::AsyncTaskScheduled(event->target()->GetExecutionContext(),
                             event->type(), event);
   pending_events_.insert(event);
-  // This queue is unthrottled because throttling event tasks may break existing
-  // web pages. For example, throttling IndexedDB events may break scenarios
-  // where several tabs, some of which are backgrounded, access the same
-  // database concurrently. See also comments in the ctor of
-  // DOMWindowEventQueueTimer.
-  // TODO(nhiroki): Callers of enqueueEvent() should specify the task type.
-  TaskRunnerHelper::Get(TaskType::kUnthrottled, worker_global_scope_.Get())
-      ->PostTask(BLINK_FROM_HERE,
-                 WTF::Bind(&WorkerEventQueue::DispatchEvent,
-                           WrapPersistent(this), WrapWeakPersistent(event)));
+  worker_global_scope_->GetThread()->PostTask(
+      BLINK_FROM_HERE,
+      WTF::Bind(&WorkerEventQueue::DispatchEvent, WrapPersistent(this),
+                WrapWeakPersistent(event)));
   return true;
 }