Worker: Introduce per-global-scope task scheduler

third_party/WebKit/Source/platform/scheduler/child/worker_global_scope_scheduler.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 THIRD_PARTY_WEBKIT_PUBLIC_PLATFORM_SCHEDULER_WORKER_GLOBAL_SCOPE_SCHEDULER_H_
+#define THIRD_PARTY_WEBKIT_PUBLIC_PLATFORM_SCHEDULER_WORKER_GLOBAL_SCOPE_SCHEDULER_H_
+
+#include "platform/scheduler/child/web_task_runner_impl.h"
+#include "public/platform/WebCommon.h"
+#include "public/platform/scheduler/base/task_queue.h"
+
+namespace blink {
+namespace scheduler {
+
+class WorkerScheduler;
+
+// A scheduler provides per-global-scope task queues. This is constructed when a
+// global scope is created and destructed when it's closed.
+//
+// Unless stated otherwise, all methods must be called on the worker thread.
+class BLINK_PLATFORM_EXPORT WorkerGlobalScopeScheduler {
+ public:
+  explicit WorkerGlobalScopeScheduler(WorkerScheduler* worker_scheduler);
+  ~WorkerGlobalScopeScheduler();
+
+  // Unregisters the task queues and cancels tasks in them.
+  void Dispose();
+
+  // Returns the WebTaskRunner for tasks which should never get throttled. This
+  // can be called from any thread.
+  RefPtr<WebTaskRunner> UnthrottledTaskRunner() {
+    return unthrottled_task_runner_;
+  }
+
+  // TODO(nhiroki): Add mechanism to throttle/suspend tasks in response to the
+  // state of the parent document (https://crbug.com/670534).
+
+ private:
+  RefPtr<WebTaskRunnerImpl> unthrottled_task_runner_;
+
+#if DCHECK_IS_ON()
+  bool is_disposed_ = false;
+#endif
+};
+
+}  // namespace scheduler
+}  // namespace blink
+
+#endif  // THIRD_PARTY_WEBKIT_PUBLIC_PLATFORM_SCHEDULER_WORKER_GLOBAL_SCOPE_SCHEDULER_H_