Worker: Introduce per-global-scope task scheduler

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

Index: third_party/WebKit/Source/core/workers/WorkerBackingThread.cpp
diff --git a/third_party/WebKit/Source/core/workers/WorkerBackingThread.cpp b/third_party/WebKit/Source/core/workers/WorkerBackingThread.cpp
index db7bd8a42c88545cdaabbae4f2648ca04902daf0..99a0a0bad41a2188d16ecc0f0ef3d985778a930c 100644
--- a/third_party/WebKit/Source/core/workers/WorkerBackingThread.cpp
+++ b/third_party/WebKit/Source/core/workers/WorkerBackingThread.cpp
@@ -14,6 +14,8 @@
 #include "platform/CrossThreadFunctional.h"
 #include "platform/RuntimeEnabledFeatures.h"
 #include "platform/WebThreadSupportingGC.h"
+#include "platform/scheduler/child/webthread_impl_for_worker_scheduler.h"
+#include "platform/scheduler/child/worker_global_scope_scheduler.h"
 #include "platform/wtf/PtrUtil.h"
 #include "public/platform/Platform.h"
 #include "public/platform/WebTraceLocation.h"
@@ -98,6 +100,15 @@ void WorkerBackingThread::Shutdown() {
   isolate_ = nullptr;
 }
 
+std::unique_ptr<scheduler::WorkerGlobalScopeScheduler>
+WorkerBackingThread::CreateGlobalScopeScheduler() {
+  scheduler::WebThreadImplForWorkerScheduler& web_thread_for_worker =
+      static_cast<scheduler::WebThreadImplForWorkerScheduler&>(
+          BackingThread().PlatformThread());
+  return WTF::MakeUnique<scheduler::WorkerGlobalScopeScheduler>(
+      web_thread_for_worker.GetWorkerScheduler());
+}
+
 // static
 void WorkerBackingThread::MemoryPressureNotificationToWorkerThreadIsolates(
     v8::MemoryPressureLevel level) {