Move throttling of background timers into the renderer scheduler

components/scheduler/base/task_queue.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 COMPONENTS_SCHEDULER_BASE_TASK_QUEUE_H_
 #define COMPONENTS_SCHEDULER_BASE_TASK_QUEUE_H_
 
 #include "base/message_loop/message_loop.h"
 #include "base/single_thread_task_runner.h"
 #include "components/scheduler/scheduler_export.h"
 
 namespace scheduler {
 class TimeDomain;
 
 class SCHEDULER_EXPORT TaskQueue : public base::SingleThreadTaskRunner {
  public:
   TaskQueue() {}
 
   // Unregisters the task queue after which no tasks posted to it will run and
   // the TaskQueueManager's reference to it will be released soon.
   virtual void UnregisterTaskQueue() = 0;
 
-  // Post a delayed task at an absolute desired run time instead of a time
-  // delta from the current time.
-  virtual bool PostDelayedTaskAt(const tracked_objects::Location& from_here,
-                                 const base::Closure& task,
-                                 base::TimeTicks desired_run_time) = 0;
-
   enum QueuePriority {
     // Queues with control priority will run before any other queue, and will
     // explicitly starve other queues. Typically this should only be used for
     // private queues which perform control operations.
     CONTROL_PRIORITY,
     // Queues with high priority will be selected preferentially over normal or
     // best effort queues. The selector will ensure that high priority queues
     // cannot completely starve normal priority queues.
     HIGH_PRIORITY,
     // Queues with normal priority are the default.
@@ skipping 99 matching lines @@
     TimeDomain* time_domain;
     bool should_notify_observers;
   };
 
   // Returns true if the queue priority is not
   // TaskQueueSelector::DISABLED_PRIORITY. NOTE this must be called on the
   // thread this TaskQueue was created by.
   virtual bool IsQueueEnabled() const = 0;
 
   // Returns true if there no tasks in either the work or incoming task queue.
+  // This method ignores delayed tasks that are scheduled to run in the future.
   // Note that this function involves taking a lock, so calling it has some
   // overhead. NOTE this must be called on the thread this TaskQueue was created
   // by.
-  virtual bool IsQueueEmpty() const;
+  virtual bool HasPendingImmediateTask() const;

[Sami, 2015/11/25 17:12:25]

Just remembered that we also have GetQueueState(). Could you add a TODO for
maybe getting rid of these two helpers if favor of a new queue state?

[alex clarke (OOO till 29th), 2015/11/26 18:43:27]

I mostly did that :)  I suppose I could get rid of HasPendingImmediateTask too,
but it makes the two call sites ugly. 

+
+  // Returns true if there is one or more delayed tasks scheduled to run in the
+  // future. Can be called on any thread.
+  virtual bool HasPendingDelayedTask() const = 0;
 
   // Returns the QueueState. Note that this function involves taking a lock, so
   // calling it has some overhead.
   virtual QueueState GetQueueState() const = 0;
 
   // Can be called on any thread.
   virtual const char* GetName() const = 0;
 
   // Set the priority of the queue to |priority|. NOTE this must be called on
   // the thread this TaskQueue was created by.
@@ skipping 25 matching lines @@
 
  protected:
   ~TaskQueue() override {}
 
   DISALLOW_COPY_AND_ASSIGN(TaskQueue);
 };
 
 }  // namespace scheduler
 
 #endif  // COMPONENTS_SCHEDULER_BASE_TASK_QUEUE_H_