Refactor Environment Config Out of TaskSchedulerImpl

base/task_scheduler/environment_config.cc

+// Copyright 2017 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/environment_config.h"
+
+namespace base {
+namespace internal {
+
+size_t GetEnvironmentIndexForTraits(const 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 internal
+}  // namespace base