[reference - do not submit] Always create four pools in TaskSchedulerImpl.

base/task_scheduler/scheduler_worker_pool_params.cc

 // 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.
 
 #include "base/task_scheduler/scheduler_worker_pool_params.h"
 
 namespace base {
 
+SchedulerWorkerPoolParams::SchedulerWorkerPoolParams()
+    : standby_thread_policy_(StandbyThreadPolicy::ONE),
+      max_threads_(0),
+      backward_compatibility_(SchedulerBackwardCompatibility::DISABLED) {}
+
 SchedulerWorkerPoolParams::SchedulerWorkerPoolParams(
-    const std::string& name,
-    ThreadPriority priority_hint,
     StandbyThreadPolicy standby_thread_policy,
     int max_threads,
     TimeDelta suggested_reclaim_time,
     SchedulerBackwardCompatibility backward_compatibility)
-    : name_(name),
-      priority_hint_(priority_hint),
-      standby_thread_policy_(standby_thread_policy),
+    : standby_thread_policy_(standby_thread_policy),
       max_threads_(max_threads),
       suggested_reclaim_time_(suggested_reclaim_time),
       backward_compatibility_(backward_compatibility) {}
 
 SchedulerWorkerPoolParams::SchedulerWorkerPoolParams(
     const SchedulerWorkerPoolParams& other) = default;
 
 SchedulerWorkerPoolParams& SchedulerWorkerPoolParams::operator=(
     const SchedulerWorkerPoolParams& other) = default;
 
+bool SchedulerWorkerPoolParams::IsValid() const {
+  return max_threads_ > 0 && suggested_reclaim_time_ >= TimeDelta();
+}
+
 }  // namespace base