Worker: Introduce per-global-scope task scheduler

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

+// 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.
+
+#include "core/workers/WorkerTaskRunners.h"
+
+#include "core/workers/WorkerOrWorkletGlobalScope.h"
+#include "platform/WebTaskRunner.h"
+#include "platform/wtf/Assertions.h"
+#include "public/platform/Platform.h"
+
+namespace blink {
+
+RefPtr<WorkerTaskRunners> WorkerTaskRunners::Create(
+    WorkerOrWorkletGlobalScope* global_scope) {
+  return AdoptRef(new WorkerTaskRunners(global_scope));
+}
+
+WorkerTaskRunners::WorkerTaskRunners(WorkerOrWorkletGlobalScope* global_scope) {
+  DCHECK(global_scope);
+  DCHECK(global_scope->IsContextThread());
+  for (unsigned i = 0; i < static_cast<unsigned>(TaskType::kNumberOfTaskTypes);
+       ++i) {
+    TaskType type = static_cast<TaskType>(i);
+    task_runners_.insert(type, TaskRunnerHelper::Get(type, global_scope));
+  }
+}
+
+RefPtr<WebTaskRunner> WorkerTaskRunners::Get(TaskType type) {
+  DCHECK_GT(TaskType::kNumberOfTaskTypes, type);
+  return task_runners_.at(type);

[Sami, 2017/04/12 15:54:06]

Is there some benefit to caching runners in |task_runners_| that I'm not seeing?
It seems like we could just call TaskRunnerHelper::Get directly here, no?

[kinuko, 2017/04/13 01:46:59]

Yeah, (in case it wasn't clear) I agree with this comment.

[nhiroki, 2017/04/13 08:23:50]

I removed WorkerTaskRunners. The original motivation of WorkerTaskRunenrs is
here:
https://codereview.chromium.org/2806623004/diff/40001/third_party/WebKit/Sour...

At first, I think it could be clearer to separate the interfaces into
TaskRunnerHelper for same-thread-postTask and
ParentFrameTaskRunners/WorkerTaskRunners for cross-thread postTask. After
offline chat with kinuko@, we decided to unify them into TaskRunnerHelper for
simplicity and reconsider the cross-thread postTask interface later.

+}
+
+}  // namespace blink