Worker: Introduce per-global-scope task scheduler

third_party/WebKit/Source/core/workers/WorkerTaskRunners.h

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef WorkerTaskRunners_h
+#define WorkerTaskRunners_h
+
+#include <memory>
+#include "core/CoreExport.h"
+#include "core/dom/TaskRunnerHelper.h"
+#include "platform/wtf/HashMap.h"
+#include "platform/wtf/Noncopyable.h"
+#include "platform/wtf/PassRefPtr.h"
+#include "platform/wtf/RefPtr.h"
+#include "platform/wtf/ThreadSafeRefCounted.h"
+
+namespace blink {
+
+class WebTaskRunner;
+class WorkerOrWorkletGlobalScope;
+
+// Represents a set of task runners of the worker/worklet global context. This
+// could be accessed from any threads and must be initialized on the thread
+// where the context is running.
+class CORE_EXPORT WorkerTaskRunners final
+    : public ThreadSafeRefCounted<WorkerTaskRunners> {
+  WTF_MAKE_NONCOPYABLE(WorkerTaskRunners);
+
+ public:
+  static RefPtr<WorkerTaskRunners> Create(WorkerOrWorkletGlobalScope*);
+
+  RefPtr<WebTaskRunner> Get(TaskType);
+
+ private:
+  using TaskRunnerHashMap = HashMap<TaskType,
+                                    RefPtr<WebTaskRunner>,
+                                    WTF::IntHash<TaskType>,
+                                    TaskTypeTraits>;
+
+  explicit WorkerTaskRunners(WorkerOrWorkletGlobalScope*);
+
+  TaskRunnerHashMap task_runners_;
+};
+
+}  // namespace blink
+
+#endif  // WorkerTaskRunners_h