scheduler: Return a base::SingleThreadTaskRunner for the default task runner.

components/scheduler/child/web_scheduler_impl.h

 // Copyright 2015 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 CONTENT_CHILD_SCHEDULER_BASE_WEB_SCHEDULER_IMPL_H_
 #define CONTENT_CHILD_SCHEDULER_BASE_WEB_SCHEDULER_IMPL_H_
 
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/time/time.h"
@@ skipping 11 matching lines @@
 class SingleThreadIdleTaskRunner;
 class TaskQueue;
 class WebTaskRunnerImpl;
 
 class SCHEDULER_EXPORT WebSchedulerImpl : public blink::WebScheduler {
  public:
   WebSchedulerImpl(
       ChildScheduler* child_scheduler,
       scoped_refptr<SingleThreadIdleTaskRunner> idle_task_runner,
       scoped_refptr<base::SingleThreadTaskRunner> loading_task_runner,
-      scoped_refptr<TaskQueue> timer_task_runner);
+      scoped_refptr<base::SingleThreadTaskRunner> timer_task_runner);
   ~WebSchedulerImpl() override;
 
   // blink::WebScheduler implementation:
   void shutdown() override;
   bool shouldYieldForHighPriorityWork() override;
   bool canExceedIdleDeadlineIfRequired() override;
   void postIdleTask(const blink::WebTraceLocation& location,
                     blink::WebThread::IdleTask* task) override;
   void postNonNestableIdleTask(const blink::WebTraceLocation& location,
                                blink::WebThread::IdleTask* task) override;
   void postIdleTaskAfterWakeup(const blink::WebTraceLocation& location,
                                blink::WebThread::IdleTask* task) override;
   blink::WebTaskRunner* loadingTaskRunner() override;
   blink::WebTaskRunner* timerTaskRunner() override;
   blink::WebPassOwnPtr<blink::WebViewScheduler> createWebViewScheduler(
       blink::WebView*) override;
   void suspendTimerQueue() override {}
   void resumeTimerQueue() override {}
   void addPendingNavigation() override {}
   void removePendingNavigation() override {}
   void onNavigationStarted() override {}
 
  private:
   static void runIdleTask(scoped_ptr<blink::WebThread::IdleTask> task,
                           base::TimeTicks deadline);
 
   ChildScheduler* child_scheduler_;  // NOT OWNED
   scoped_refptr<SingleThreadIdleTaskRunner> idle_task_runner_;
-  scoped_refptr<TaskQueue> timer_task_runner_;
+  scoped_refptr<base::SingleThreadTaskRunner> timer_task_runner_;
   scoped_ptr<WebTaskRunnerImpl> loading_web_task_runner_;
   scoped_ptr<WebTaskRunnerImpl> timer_web_task_runner_;
 };
 
 }  // namespace scheduler
 
 #endif  // CONTENT_CHILD_SCHEDULER_BASE_WEB_SCHEDULER_IMPL_H_