Move blink scheduler implementation into a component

content/child/webthread_base.h

 // Copyright 2014 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_WEBTHREAD_BASE_H_
 #define CONTENT_CHILD_WEBTHREAD_BASE_H_
 
 #include <map>
 
 #include "base/memory/scoped_ptr.h"
 #include "base/threading/thread.h"
 #include "content/common/content_export.h"
 #include "third_party/WebKit/public/platform/WebThread.h"
 
 namespace blink {
 class WebTraceLocation;
 }
 
+namespace scheduler {
+class SingleThreadIdleTaskRunner;
+}
+
 namespace content {
-class SingleThreadIdleTaskRunner;
 
 class CONTENT_EXPORT WebThreadBase : public blink::WebThread {
  public:
   virtual ~WebThreadBase();
 
   // blink::WebThread implementation.
   virtual bool isCurrentThread() const;
   virtual blink::PlatformThreadId threadId() const = 0;
 
   virtual void postTask(const blink::WebTraceLocation& location, Task* task);
@@ skipping 10 matching lines @@
 
   virtual void addTaskObserver(TaskObserver* observer);
   virtual void removeTaskObserver(TaskObserver* observer);
 
   // Returns the base::Bind-compatible task runner for posting tasks to this
   // thread. Can be called from any thread.
   virtual base::SingleThreadTaskRunner* TaskRunner() const = 0;
 
   // Returns the base::Bind-compatible task runner for posting idle tasks to
   // this thread. Can be called from any thread.
-  virtual SingleThreadIdleTaskRunner* IdleTaskRunner() const = 0;
+  virtual scheduler::SingleThreadIdleTaskRunner* IdleTaskRunner() const = 0;
 
  protected:
   class TaskObserverAdapter;
 
   WebThreadBase();
 
   // Returns the underlying MessageLoop for this thread. Only used for entering
   // and exiting a nested run loop. Only called on the thread that the
   // WebThread belongs to.
   virtual base::MessageLoop* MessageLoop() const = 0;
 
   virtual void AddTaskObserverInternal(
       base::MessageLoop::TaskObserver* observer);
   virtual void RemoveTaskObserverInternal(
       base::MessageLoop::TaskObserver* observer);
 
   static void RunWebThreadTask(scoped_ptr<blink::WebThread::Task> task);
   static void RunWebThreadIdleTask(
       scoped_ptr<blink::WebThread::IdleTask> idle_task,
       base::TimeTicks deadline);
 
  private:
   typedef std::map<TaskObserver*, TaskObserverAdapter*> TaskObserverMap;
   TaskObserverMap task_observer_map_;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_CHILD_WEBTHREAD_BASE_H_