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;
 
 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 85 matching lines @@
   // may be throttled.
   //
   // UnspecedLoading type should be used for all tasks associated with
   // loading page content, UnspecedTimer should be used for all other purposes.
   kUnspecedTimer,
   kUnspecedLoading,
 
   // Tasks that must not be throttled should be posted here, but the usage
   // should be very limited.
   kUnthrottled,
+
+  // A new task type should be added before this.
+  kNumberOfTaskTypes,
 };
 
 // HashTraits for TaskType.
 struct TaskTypeTraits : WTF::GenericHashTraits<TaskType> {
   static const bool kEmptyValueIsZero = false;
   static TaskType EmptyValue() { return static_cast<TaskType>(-1); }
   static void ConstructDeletedValue(TaskType& slot, bool) {
     slot = static_cast<TaskType>(-2);
   }
   static bool IsDeletedValue(TaskType value) {
     return value == static_cast<TaskType>(-2);
   }
 };
 
 // A set of helper functions to get a WebTaskRunner for TaskType and a context
 // 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*);
 };
 
 }  // namespace blink
 
 #endif