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

content/browser/browser_main_loop.cc

Index: content/browser/browser_main_loop.cc
diff --git a/content/browser/browser_main_loop.cc b/content/browser/browser_main_loop.cc
index 5a035af978b5428e5d09c223af05f0ce0b5a9975..098e9f3391ac107760c03e00449585e21f324fd4 100644
--- a/content/browser/browser_main_loop.cc
+++ b/content/browser/browser_main_loop.cc
@@ -34,7 +34,6 @@
 #include "base/system_monitor/system_monitor.h"
 #include "base/task_scheduler/initialization_util.h"
 #include "base/task_scheduler/post_task.h"
-#include "base/task_scheduler/scheduler_worker_pool_params.h"
 #include "base/task_scheduler/task_scheduler.h"
 #include "base/task_scheduler/task_traits.h"
 #include "base/threading/sequenced_worker_pool.h"
@@ -419,67 +418,51 @@ enum WorkerPoolType : size_t {
   WORKER_POOL_COUNT  // Always last.
 };
 
-std::vector<base::SchedulerWorkerPoolParams>
-GetDefaultSchedulerWorkerPoolParams() {
+std::unique_ptr<base::TaskSchedulerInitParams>
+GetDefaultTaskSchedulerInitParams() {
   using StandbyThreadPolicy =
       base::SchedulerWorkerPoolParams::StandbyThreadPolicy;
-  using ThreadPriority = base::ThreadPriority;
-  std::vector<base::SchedulerWorkerPoolParams> params_vector;
 #if defined(OS_ANDROID)
-  params_vector.emplace_back(
-      "Background", ThreadPriority::BACKGROUND, StandbyThreadPolicy::ONE,
-       base::RecommendedMaxNumberOfThreadsInPool(2, 8, 0.1, 0),
-       base::TimeDelta::FromSeconds(30));
-  params_vector.emplace_back(
-      "BackgroundBlocking", ThreadPriority::BACKGROUND,
-      StandbyThreadPolicy::ONE,
-      base::RecommendedMaxNumberOfThreadsInPool(2, 8, 0.1, 0),
-      base::TimeDelta::FromSeconds(30));
-  params_vector.emplace_back(
-      "Foreground", ThreadPriority::NORMAL, StandbyThreadPolicy::ONE,
-       base::RecommendedMaxNumberOfThreadsInPool(3, 8, 0.3, 0),
-       base::TimeDelta::FromSeconds(30));
-  params_vector.emplace_back(
-      "ForegroundBlocking", ThreadPriority::NORMAL, StandbyThreadPolicy::ONE,
-      base::RecommendedMaxNumberOfThreadsInPool(3, 8, 0.3, 0),
-      base::TimeDelta::FromSeconds(30));
+  return base::MakeUnique<base::TaskSchedulerInitParams>(
+      base::SchedulerWorkerPoolParams(
+          StandbyThreadPolicy::ONE,
+          base::RecommendedMaxNumberOfThreadsInPool(2, 8, 0.1, 0),
+          base::TimeDelta::FromSeconds(30)),
+      base::SchedulerWorkerPoolParams(
+          StandbyThreadPolicy::ONE,
+          base::RecommendedMaxNumberOfThreadsInPool(2, 8, 0.1, 0),
+          base::TimeDelta::FromSeconds(30)),
+      base::SchedulerWorkerPoolParams(
+          StandbyThreadPolicy::ONE,
+          base::RecommendedMaxNumberOfThreadsInPool(3, 8, 0.3, 0),
+          base::TimeDelta::FromSeconds(30)),
+      base::SchedulerWorkerPoolParams(
+          StandbyThreadPolicy::ONE,
+          base::RecommendedMaxNumberOfThreadsInPool(3, 8, 0.3, 0),
+          base::TimeDelta::FromSeconds(30)));
 #else
-  params_vector.emplace_back(
-      "Background", ThreadPriority::BACKGROUND, StandbyThreadPolicy::ONE,
-       base::RecommendedMaxNumberOfThreadsInPool(3, 8, 0.1, 0),
-       base::TimeDelta::FromSeconds(30));
-  params_vector.emplace_back(
-      "BackgroundBlocking", ThreadPriority::BACKGROUND,
-      StandbyThreadPolicy::ONE,
-      base::RecommendedMaxNumberOfThreadsInPool(3, 8, 0.1, 0),
-      base::TimeDelta::FromSeconds(30));
-  params_vector.emplace_back(
-      "Foreground", ThreadPriority::NORMAL, StandbyThreadPolicy::ONE,
-       base::RecommendedMaxNumberOfThreadsInPool(8, 32, 0.3, 0),
-       base::TimeDelta::FromSeconds(30));
-  // Tasks posted to SequencedWorkerPool or BrowserThreadImpl may be redirected
-  // to this pool. Since COM STA is initialized in these environments, it must
-  // also be initialized in this pool.
-  params_vector.emplace_back(
-      "ForegroundBlocking", ThreadPriority::NORMAL, StandbyThreadPolicy::ONE,
-      base::RecommendedMaxNumberOfThreadsInPool(8, 32, 0.3, 0),
-      base::TimeDelta::FromSeconds(30),
-      base::SchedulerBackwardCompatibility::INIT_COM_STA);
+  return base::MakeUnique<base::TaskSchedulerInitParams>(
+      base::SchedulerWorkerPoolParams(
+          StandbyThreadPolicy::ONE,
+          base::RecommendedMaxNumberOfThreadsInPool(3, 8, 0.1, 0),
+          base::TimeDelta::FromSeconds(30)),
+      base::SchedulerWorkerPoolParams(
+          StandbyThreadPolicy::ONE,
+          base::RecommendedMaxNumberOfThreadsInPool(3, 8, 0.1, 0),
+          base::TimeDelta::FromSeconds(30)),
+      base::SchedulerWorkerPoolParams(
+          StandbyThreadPolicy::ONE,
+          base::RecommendedMaxNumberOfThreadsInPool(8, 32, 0.3, 0),
+          base::TimeDelta::FromSeconds(30)),
+      // Tasks posted to SequencedWorkerPool or BrowserThreadImpl may be
+      // redirected to this pool. Since COM STA is initialized in these
+      // environments, it must also be initialized in this pool.
+      base::SchedulerWorkerPoolParams(
+          StandbyThreadPolicy::ONE,
+          base::RecommendedMaxNumberOfThreadsInPool(8, 32, 0.3, 0),
+          base::TimeDelta::FromSeconds(30),
+          base::SchedulerBackwardCompatibility::INIT_COM_STA));
 #endif
-  DCHECK_EQ(WORKER_POOL_COUNT, params_vector.size());
-  return params_vector;
-}
-
-// Returns the worker pool index for |traits| defaulting to FOREGROUND or
-// FOREGROUND_BLOCKING on any other priorities based off of worker pools defined
-// in GetDefaultSchedulerWorkerPoolParams().
-size_t DefaultBrowserWorkerPoolIndexForTraits(const base::TaskTraits& traits) {
-  const bool is_background =
-      traits.priority() == base::TaskPriority::BACKGROUND;
-  if (traits.may_block() || traits.with_base_sync_primitives())
-    return is_background ? BACKGROUND_BLOCKING : FOREGROUND_BLOCKING;
-
-  return is_background ? BACKGROUND : FOREGROUND;
 }
 
 }  // namespace
@@ -993,20 +976,16 @@ void BrowserMainLoop::CreateStartupTasks() {
 int BrowserMainLoop::CreateThreads() {
   TRACE_EVENT0("startup,rail", "BrowserMainLoop::CreateThreads");
 
-  std::vector<base::SchedulerWorkerPoolParams> params_vector;
-  base::TaskScheduler::WorkerPoolIndexForTraitsCallback
-      index_to_traits_callback;
-  GetContentClient()->browser()->GetTaskSchedulerInitializationParams(
-      &params_vector, &index_to_traits_callback);
-
-  if (params_vector.empty() || index_to_traits_callback.is_null()) {
-    params_vector = GetDefaultSchedulerWorkerPoolParams();
-    index_to_traits_callback =
-        base::Bind(&DefaultBrowserWorkerPoolIndexForTraits);
+  auto task_scheduler_init_params =
+      GetContentClient()->browser()->GetTaskSchedulerInitParams();
+  if (!task_scheduler_init_params) {
+    task_scheduler_init_params = GetDefaultTaskSchedulerInitParams();
   }
+  DCHECK(task_scheduler_init_params);
+  DCHECK(task_scheduler_init_params->IsValid());
 
   base::TaskScheduler::CreateAndSetDefaultTaskScheduler(
-      params_vector, index_to_traits_callback);
+      "", *task_scheduler_init_params.get());
 
   GetContentClient()->browser()->PerformExperimentalTaskSchedulerRedirections();