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

base/task_scheduler/scheduler_worker_pool_params.h

Index: base/task_scheduler/scheduler_worker_pool_params.h
diff --git a/base/task_scheduler/scheduler_worker_pool_params.h b/base/task_scheduler/scheduler_worker_pool_params.h
index 4c0548c5226b15d2b94f2a46ede76dde9e48181c..788266fe98d78c38d56ecc52e92972415c666f6d 100644
--- a/base/task_scheduler/scheduler_worker_pool_params.h
+++ b/base/task_scheduler/scheduler_worker_pool_params.h
@@ -5,10 +5,7 @@
 #ifndef BASE_TASK_SCHEDULER_SCHEDULER_WORKER_POOL_PARAMS_H_
 #define BASE_TASK_SCHEDULER_SCHEDULER_WORKER_POOL_PARAMS_H_
 
-#include <string>
-
 #include "base/task_scheduler/scheduler_worker_params.h"
-#include "base/threading/platform_thread.h"
 #include "base/time/time.h"
 
 namespace base {
@@ -23,29 +20,28 @@ class BASE_EXPORT SchedulerWorkerPoolParams final {
     ONE,
   };
 
-  // Construct a scheduler worker pool parameter object. |name| will be used to
-  // label the pool's threads ("TaskScheduler" + |name| + index) and histograms
-  // ("TaskScheduler." + histogram name + "." + |name| + extra suffixes). The
-  // pool will contain up to |max_threads|. |priority_hint| is the preferred
-  // thread priority; the actual thread priority depends on shutdown state and
-  // platform capabilities. |standby_thread_policy| indicates whether an idle
+  // Constructs an invalid scheduler worker pool parameter object.
+  SchedulerWorkerPoolParams();
+
+  // Constructs a scheduler worker pool parameter object. The pool will contain
+  // up to |max_threads|. |standby_thread_policy| indicates whether an idle
   // thread should be kept alive on standby. |suggested_reclaim_time| sets a
   // suggestion on when to reclaim idle threads. The pool is free to ignore this
   // value for performance or correctness reasons. |backward_compatibility|
   // indicates whether backward compatibility is enabled.
   SchedulerWorkerPoolParams(
-      const std::string& name,
-      ThreadPriority priority_hint,
       StandbyThreadPolicy standby_thread_policy,
       int max_threads,
       TimeDelta suggested_reclaim_time,
       SchedulerBackwardCompatibility backward_compatibility =
           SchedulerBackwardCompatibility::DISABLED);
+
   SchedulerWorkerPoolParams(const SchedulerWorkerPoolParams& other);
   SchedulerWorkerPoolParams& operator=(const SchedulerWorkerPoolParams& other);
 
-  const std::string& name() const { return name_; }
-  ThreadPriority priority_hint() const { return priority_hint_; }
+  // Returns true if this object can be used to initialize a worker pool.
+  bool IsValid() const;
+
   StandbyThreadPolicy standby_thread_policy() const {
     return standby_thread_policy_;
   }
@@ -56,8 +52,6 @@ class BASE_EXPORT SchedulerWorkerPoolParams final {
   }
 
  private:
-  std::string name_;
-  ThreadPriority priority_hint_;
   StandbyThreadPolicy standby_thread_policy_;
   size_t max_threads_;
   TimeDelta suggested_reclaim_time_;