Use TIMER_SLACK_MAXIMUM on the TaskScheduler service thread.

base/task_scheduler/post_task.h

 // Copyright 2016 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 BASE_TASK_SCHEDULER_POST_TASK_H_
 #define BASE_TASK_SCHEDULER_POST_TASK_H_
 
 #include "base/base_export.h"
 #include "base/callback_forward.h"
 #include "base/location.h"
@@ skipping 68 matching lines @@
 // Posts |task| with specific |traits| to the TaskScheduler and posts |reply| on
 // the caller's execution context (i.e. same sequence or thread and same
 // TaskTraits if applicable) when |task| completes. Can only be called when
 // SequencedTaskRunnerHandle::IsSet().
 BASE_EXPORT void PostTaskWithTraitsAndReply(
     const tracked_objects::Location& from_here,
     const TaskTraits& traits,
     const Closure& task,
     const Closure& reply);
 
+// Delayed tasks posted to TaskRunners returned by the functions below may be
+// coalesced (i.e. delays may be adjusted to reduce the number of wakeups and
+// hence power consumption).
+
 // Returns a TaskRunner whose PostTask invocations result in scheduling tasks
 // using |traits|. Tasks may run in any order and in parallel.
 BASE_EXPORT scoped_refptr<TaskRunner> CreateTaskRunnerWithTraits(
     const TaskTraits& traits);
 
 // Returns a SequencedTaskRunner whose PostTask invocations result in scheduling
 // tasks using |traits|. Tasks run one at a time in posting order.
 BASE_EXPORT scoped_refptr<SequencedTaskRunner>
 CreateSequencedTaskRunnerWithTraits(const TaskTraits& traits);
 
 // Returns a SingleThreadTaskRunner whose PostTask invocations result in
 // scheduling tasks using |traits|. Tasks run on a single thread in posting
 // order.
 //
 // If all you need is to make sure that tasks don't run concurrently (e.g.
 // because they access a data structure which is not thread-safe), use
 // CreateSequencedTaskRunnerWithTraits(). Only use this if you rely on a thread-
 // affine API (it might be safer to assume thread-affinity when dealing with
 // under-documented third-party APIs, e.g. other OS') or share data across tasks
 // using thread-local storage.
 BASE_EXPORT scoped_refptr<SingleThreadTaskRunner>
 CreateSingleThreadTaskRunnerWithTraits(const TaskTraits& traits);
 
 }  // namespace base
 
 #endif  // BASE_TASK_SCHEDULER_POST_TASK_H_