Worker: Introduce per-global-scope task scheduler

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

Index: third_party/WebKit/Source/core/dom/TaskRunnerHelper.h
diff --git a/third_party/WebKit/Source/core/dom/TaskRunnerHelper.h b/third_party/WebKit/Source/core/dom/TaskRunnerHelper.h
index 4a08df5ab2851b49f8b26f5ece82f310abd86af6..bb4fba6d92174aa61a1f6df24836e45d4bf51305 100644
--- a/third_party/WebKit/Source/core/dom/TaskRunnerHelper.h
+++ b/third_party/WebKit/Source/core/dom/TaskRunnerHelper.h
@@ -16,6 +16,7 @@ class ExecutionContext;
 class LocalFrame;
 class ScriptState;
 class WebTaskRunner;
+class WorkerThread;
 
 enum class TaskType : unsigned {
   // Speced tasks and related internal tasks should be posted to one of
@@ -146,6 +147,7 @@ class CORE_EXPORT TaskRunnerHelper final {
   static RefPtr<WebTaskRunner> get(TaskType, Document*);
   static RefPtr<WebTaskRunner> get(TaskType, ExecutionContext*);
   static RefPtr<WebTaskRunner> get(TaskType, ScriptState*);
+  static RefPtr<WebTaskRunner> get(TaskType, WorkerThread*);
 };
 
 }  // namespace blink