scheduler: Don't access weak pointers on foreign threads

content/renderer/scheduler/task_queue_manager.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_RENDERER_SCHEDULER_TASK_QUEUE_MANAGER_H_
 #define CONTENT_RENDERER_SCHEDULER_TASK_QUEUE_MANAGER_H_
 
 #include "base/atomic_sequence_num.h"
 #include "base/debug/task_annotator.h"
 #include "base/macros.h"
-#include "base/memory/scoped_vector.h"
 #include "base/memory/weak_ptr.h"
 #include "base/pending_task.h"
 #include "base/single_thread_task_runner.h"
 #include "base/synchronization/lock.h"
 #include "base/threading/thread_checker.h"
 #include "content/common/content_export.h"
 
 namespace content {
 namespace internal {
-class TaskRunner;
-struct TaskQueue;
+class TaskQueue;
 }
 class TaskQueueSelector;
 
 // The task queue manager provides N task queues and a selector interface for
 // choosing which task queue to service next. Each task queue consists of two
 // sub queues:
 //
 // 1. Incoming task queue. Tasks that are posted get immediately appended here.
 //    When a task is appended into an empty incoming queue, the task manager
 //    work function (DoWork) is scheduled to run on the main task runner.
@@ skipping 29 matching lines @@
   // scheduled for execution.
   //
   // This function only needs to be called if automatic pumping is disabled
   // for |queue_index|. See |SetQueueAutoPump|. By default automatic pumping is
   // enabled for all queues.
   void PumpQueue(size_t queue_index);
 
   // Returns true if there no tasks in either the work or incoming task queue
   // identified by |queue_index|. Note that this function involves taking a
   // lock, so calling it has some overhead.
-  bool IsQueueEmpty(size_t queue_index);
+  bool IsQueueEmpty(size_t queue_index) const;
 
  private:
-  friend class internal::TaskRunner;
+  friend class internal::TaskQueue;
 
-  // Adds a task at the end of the incoming task queue for |queue_index| and
-  // schedules a call to DoWork() if the incoming queue was empty and automatic
-  // pumping is enabled. Can be called on an arbitrary thread.
-  void EnqueueTask(size_t queue_index, const base::PendingTask& pending_task);
+  // Called by the task queue to register a new pending task and allocate a
+  // sequence number for it.
+  void DidQueueTask(base::PendingTask* pending_task);
 
   // Post a task to call DoWork() on the main task runner.
   void PostDoWorkOnMainRunner();
 
   // Use the selector to choose a pending task and run it.
   void DoWork();
 
   // Reloads any empty work queues which have automatic pumping enabled.
   // Returns true if any work queue has tasks after doing this.
   bool UpdateWorkQueues();
 
   // Runs a single task from the work queue designated by |queue_index|. The
   // queue must not be empty.
   void RunTaskFromWorkQueue(size_t queue_index);
 
   bool RunsTasksOnCurrentThread() const;
-  bool PostDelayedTask(size_t queue_index,
-                       const tracked_objects::Location& from_here,
+  bool PostDelayedTask(const tracked_objects::Location& from_here,
                        const base::Closure& task,
                        base::TimeDelta delay);
-  bool PostNonNestableDelayedTask(size_t queue_index,
-                                  const tracked_objects::Location& from_here,
+  bool PostNonNestableDelayedTask(const tracked_objects::Location& from_here,
                                   const base::Closure& task,
                                   base::TimeDelta delay);
   internal::TaskQueue* Queue(size_t queue_index) const;
-  void PumpQueueLocked(internal::TaskQueue* queue);
 
-  ScopedVector<internal::TaskQueue> queues_;
+  std::vector<scoped_refptr<internal::TaskQueue>> queues_;
   base::AtomicSequenceNumber task_sequence_num_;
   base::debug::TaskAnnotator task_annotator_;
 
   base::ThreadChecker main_thread_checker_;
   scoped_refptr<base::SingleThreadTaskRunner> main_task_runner_;
   TaskQueueSelector* selector_;
 
+  base::WeakPtr<TaskQueueManager> task_queue_manager_weak_ptr_;
   base::WeakPtrFactory<TaskQueueManager> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(TaskQueueManager);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_SCHEDULER_TASK_QUEUE_MANAGER_H_