Initialize TaskScheduler with InitParams in CreateAndSetSimpleTaskScheduler().

base/task_scheduler/task_scheduler.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/task_scheduler.h"
 
 #include <algorithm>
 
 #include "base/bind.h"
 #include "base/logging.h"
@@ skipping 22 matching lines @@
           background_blocking_worker_pool_params_in),
       foreground_worker_pool_params(foreground_worker_pool_params_in),
       foreground_blocking_worker_pool_params(
           foreground_blocking_worker_pool_params_in) {}
 
 TaskScheduler::InitParams::~InitParams() = default;
 
 #if !defined(OS_NACL)
 // static
 void TaskScheduler::CreateAndSetSimpleTaskScheduler(const std::string& name) {
-  constexpr int kMinNumThreads = 1;
-  std::vector<SchedulerWorkerPoolParams> worker_pool_params_vector;
-  worker_pool_params_vector.emplace_back(
-      name, ThreadPriority::NORMAL,
-      SchedulerWorkerPoolParams::StandbyThreadPolicy::LAZY,
-      std::max(kMinNumThreads, SysInfo::NumberOfProcessors()),
-      TimeDelta::FromSeconds(30));
+  using StandbyThreadPolicy = SchedulerWorkerPoolParams::StandbyThreadPolicy;
+
+  const int num_cores = SysInfo::NumberOfProcessors();

[robliao, 2017/04/06 18:09:37]

Add a quick blurb on how we set these values:
Intentions for the simple task scheduler
Under full load...
* Background threads never outnumber foreground threads.
* The system is utilized maximally.

[fdoray, 2017/04/06 18:22:27]

Done.

+  constexpr int kBackgroundMaxThreads = 1;
+  constexpr int kBackgroundBlockingMaxThreads = 2;
+  const int kForegroundMaxThreads = std::max(1, num_cores);
+  const int kForegroundBlockingMaxThreads = std::max(2, num_cores);
+  constexpr TimeDelta kSuggestedReclaimTime = TimeDelta::FromSeconds(30);
+
   CreateAndSetDefaultTaskScheduler(
-      worker_pool_params_vector,
-      Bind([](const TaskTraits&) -> size_t { return 0; }));
+      name, {{StandbyThreadPolicy::LAZY, kBackgroundMaxThreads,
+              kSuggestedReclaimTime},
+             {StandbyThreadPolicy::LAZY, kBackgroundBlockingMaxThreads,
+              kSuggestedReclaimTime},
+             {StandbyThreadPolicy::LAZY, kForegroundMaxThreads,
+              kSuggestedReclaimTime},
+             {StandbyThreadPolicy::LAZY, kForegroundBlockingMaxThreads,
+              kSuggestedReclaimTime}});
 }
 #endif  // !defined(OS_NACL)
 
 // static
 void TaskScheduler::CreateAndSetDefaultTaskScheduler(
     const std::vector<SchedulerWorkerPoolParams>& worker_pool_params_vector,
     const WorkerPoolIndexForTraitsCallback&
         worker_pool_index_for_traits_callback) {
   SetInstance(internal::TaskSchedulerImpl::Create(
       worker_pool_params_vector, worker_pool_index_for_traits_callback));
@@ skipping 10 matching lines @@
   delete g_task_scheduler;
   g_task_scheduler = task_scheduler.release();
 }
 
 // static
 TaskScheduler* TaskScheduler::GetInstance() {
   return g_task_scheduler;
 }
 
 }  // namespace base