scheduler: Disable expensive timers during main thread user input

components/scheduler/child/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_CHILD_TASK_QUEUE_H_
 #define COMPONENTS_SCHEDULER_CHILD_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 SCHEDULER_EXPORT TaskQueue : public base::SingleThreadTaskRunner {
  public:
   TaskQueue() {}
 
   // Unregisters the task queue after which no tasks posted to it will run and
@@ skipping 140 matching lines @@
 
   // Reloads new tasks from the incoming queue into the work queue, regardless
   // of whether the work queue is empty or not. After this, the function ensures
   // that the tasks in the work queue, if any, are scheduled for execution.
   //
   // This function only needs to be called if automatic pumping is disabled.
   // By default automatic pumping is enabled for all queues. NOTE this must be
   // called on the thread this TaskQueue was created by.
   virtual void PumpQueue() = 0;
 
+  // These functions can only be called on the same thread that the task queue
+  // manager executes its tasks on.
+  virtual void AddTaskObserver(
+      base::MessageLoop::TaskObserver* task_observer) = 0;
+  virtual void RemoveTaskObserver(
+      base::MessageLoop::TaskObserver* task_observer) = 0;
+
  protected:
   ~TaskQueue() override {}
 
   DISALLOW_COPY_AND_ASSIGN(TaskQueue);
 };
 
 }  // namespace scheduler
 
 #endif  // COMPONENTS_SCHEDULER_CHILD_TASK_QUEUE_H_