scheduler: Disable expensive timers during main thread user input

components/scheduler/child/task_queue_manager.cc

 // 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.
 
 #include "components/scheduler/child/task_queue_manager.h"
 
 #include <queue>
 #include <set>
 
 #include "base/bind.h"
@@ skipping 319 matching lines @@
     // Defer non-nestable work to the main task runner.  NOTE these tasks can be
     // arbitrarily delayed so the additional delay should not be a problem.
     main_task_runner_->PostNonNestableTask(pending_task.posted_from,
                                            pending_task.task);
   } else {
     TRACE_TASK_EXECUTION("TaskQueueManager::ProcessTaskFromWorkQueue",
                          pending_task);
     if (queue->GetShouldNotifyObservers()) {
       FOR_EACH_OBSERVER(base::MessageLoop::TaskObserver, task_observers_,
                         WillProcessTask(pending_task));
+      queue->NotifyWillProcessTask(pending_task);
     }
     TRACE_EVENT1(disabled_by_default_tracing_category_,
                  "Run Task From Queue", "queue", queue->GetName());
     task_annotator_.RunTask("TaskQueueManager::PostTask", pending_task);
 
     // Detect if the TaskQueueManager just got deleted.  If this happens we must
     // not access any member variables after this point.
     if (protect->HasOneRef())
       return true;
 
     if (queue->GetShouldNotifyObservers()) {
       FOR_EACH_OBSERVER(base::MessageLoop::TaskObserver, task_observers_,
                         DidProcessTask(pending_task));
+      queue->NotifyDidProcessTask(pending_task);
     }
 
     pending_task.task.Reset();
     *out_previous_task = pending_task;
   }
   return false;
 }
 
 bool TaskQueueManager::RunsTasksOnCurrentThread() const {
   return main_task_runner_->RunsTasksOnCurrentThread();
@@ skipping 70 matching lines @@
 }
 
 void TaskQueueManager::OnTaskQueueEnabled(internal::TaskQueueImpl* queue) {
   DCHECK(main_thread_checker_.CalledOnValidThread());
   // Only schedule DoWork if there's something to do.
   if (!queue->work_queue().empty())
     MaybePostDoWorkOnMainRunner();
 }
 
 }  // namespace scheduler