Worker: Introduce per-global-scope task scheduler

third_party/WebKit/Source/core/dom/TaskRunnerHelper.h

 // Copyright 2016 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 TaskRunnerHelper_h
 #define TaskRunnerHelper_h
 
 #include "core/CoreExport.h"
 #include "platform/wtf/Allocator.h"
 #include "platform/wtf/HashTraits.h"
 
 namespace blink {
 
 class Document;
 class ExecutionContext;
 class LocalFrame;
 class ScriptState;
 class WebTaskRunner;
+class WorkerOrWorkletGlobalScope;
+class WorkerThread;
 
 enum class TaskType : unsigned {
   // Speced tasks and related internal tasks should be posted to one of
   // the following task runners. These task runners may be throttled.
 
   // https://html.spec.whatwg.org/multipage/webappapis.html#generic-task-sources
   //
   // This task source is used for features that react to DOM manipulations, such
   // as things that happen in a non-blocking fashion when an element is inserted
   // into the document.
@@ skipping 110 matching lines @@
 // object. The posted tasks are guaranteed to run in a sequence if they have the
 // same TaskType and the context objects belong to the same frame.
 class CORE_EXPORT TaskRunnerHelper final {
   STATIC_ONLY(TaskRunnerHelper);
 
  public:
   static RefPtr<WebTaskRunner> Get(TaskType, LocalFrame*);
   static RefPtr<WebTaskRunner> Get(TaskType, Document*);
   static RefPtr<WebTaskRunner> Get(TaskType, ExecutionContext*);
   static RefPtr<WebTaskRunner> Get(TaskType, ScriptState*);
+  static RefPtr<WebTaskRunner> Get(TaskType, WorkerOrWorkletGlobalScope*);
+
+  // Passing WorkerThread could be confusing but it's valid because WorkerThread

[kinuko, 2017/04/17 05:01:11]

Maybe it'd be clearer to document what this Get does before noting this caveat
(E.g. "Returns WebTaskRunners that are associated to the worker global scope
that corresponds to the given WorkerThread. Note that WorkerThread is a
per-global-scope object while the naming might sound differently. TODO:...")

[nhiroki, 2017/04/17 11:03:46]

Yeah, that makes it much clearer. Done.

+  // has one-to-one relationship with a context object.
+  // TODO(nhiroki): Rename WorkerThread to something that clarifies it's a
+  // per-global-scope object.
+  static RefPtr<WebTaskRunner> Get(TaskType, WorkerThread*);
 };
 
 }  // namespace blink
 
 #endif