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

components/task_scheduler_util/common/variations_util.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 COMPONENTS_TASK_SCHEDULER_UTIL_COMMON_VARIATIONS_UTIL_H_
 #define COMPONENTS_TASK_SCHEDULER_UTIL_COMMON_VARIATIONS_UTIL_H_
 
 #include <map>
 #include <string>
-#include <vector>
 
 #include "build/build_config.h"
 #include "base/strings/string_piece.h"
 #include "base/task_scheduler/scheduler_worker_params.h"
 #include "base/task_scheduler/scheduler_worker_pool_params.h"
-#include "base/threading/platform_thread.h"
 
 namespace base {
 class CommandLine;
 }
 
 namespace task_scheduler_util {
 
-class SchedulerImmutableWorkerPoolParams {
- public:
-  SchedulerImmutableWorkerPoolParams(
-      const char* name,
-      base::ThreadPriority priority_hint,
-      base::SchedulerBackwardCompatibility backward_compatibility =
-          base::SchedulerBackwardCompatibility::DISABLED);
-
-  const char* name() const { return name_; }
-  base::ThreadPriority priority_hint() const { return priority_hint_; }
-  base::SchedulerBackwardCompatibility backward_compatibility() const {
-    return backward_compatibility_;
-  }
-
- private:
-  const char* name_;
-  base::ThreadPriority priority_hint_;
-  base::SchedulerBackwardCompatibility backward_compatibility_;
-};
-
-// Returns a SchedulerWorkerPoolParams vector to initialize pools specified in
-// |constant_worker_pool_params_vector|. SchedulerWorkerPoolParams members
-// without a counterpart in SchedulerImmutableWorkerPoolParams are initialized
-// based of |variation_params|. Returns an empty vector on failure.
-std::vector<base::SchedulerWorkerPoolParams> GetWorkerPoolParams(
-    const std::vector<SchedulerImmutableWorkerPoolParams>&
-        constant_worker_pool_params_vector,
-    const std::map<std::string, std::string>& variation_params);
+// Builds a SchedulerWorkerPoolParams from |pool_descriptor| and
+// |backward_compatibility|. Returns an invalid SchedulerWorkerPoolParams on
+// failure.
+//
+// |pool_descriptor| is a semi-colon separated value string with the following
+// items:
+// 0. Minimum Thread Count (int)
+// 1. Maximum Thread Count (int)
+// 2. Thread Count Multiplier (double)
+// 3. Thread Count Offset (int)
+// 4. Detach Time in Milliseconds (int)
+// 5. Standby Thread Policy (string)
+// Additional values may appear as necessary and will be ignored.
+base::SchedulerWorkerPoolParams StringToVariableWorkerPoolParams(
+    const base::StringPiece pool_descriptor,
+    base::SchedulerBackwardCompatibility backward_compatibility =
+        base::SchedulerBackwardCompatibility::DISABLED);
 
 #if !defined(OS_IOS)
 // Serializes variation params from the BrowserScheduler field trial whose key
 // start with |prefix| to the --task-scheduler-variation-params switch of
 // |command_line|.
 void AddVariationParamsToCommandLine(base::StringPiece key_prefix,
                                      base::CommandLine* command_line);
 
 // Returns a map of key-value pairs deserialized from the
 // --task-scheduler-variation-params switch of |command_line|.
 std::map<std::string, std::string> GetVariationParamsFromCommandLine(
     const base::CommandLine& command_line);
 #endif  // !defined(OS_IOS)
 
 }  // namespace task_scheduler_util
 
 #endif  // COMPONENTS_TASK_SCHEDULER_UTIL_COMMON_VARIATIONS_UTIL_H_