Control TaskScheduler initialization params in renderers via field trial.

components/task_scheduler_util/renderer/initialization.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 "components/task_scheduler_util/renderer/initialization.h"
+
+#include <map>
+#include <string>
+
+#include "base/command_line.h"
+#include "base/logging.h"
+#include "base/task_scheduler/task_traits.h"
+#include "base/threading/platform_thread.h"
+#include "components/task_scheduler_util/common/variations_util.h"
+
+namespace task_scheduler_util {
+
+namespace {
+
+enum WorkerPoolType : size_t {
+  BACKGROUND = 0,
+  BACKGROUND_BLOCKING,
+  FOREGROUND,
+  FOREGROUND_BLOCKING,
+  WORKER_POOL_COUNT  // Always last.
+};
+
+}  // namespace
+
+std::vector<base::SchedulerWorkerPoolParams> GetRendererWorkerPoolParams() {
+  using ThreadPriority = base::ThreadPriority;
+  std::vector<SchedulerImmutableWorkerPoolParams> immutable_worker_pool_params;
+  DCHECK_EQ(BACKGROUND, immutable_worker_pool_params.size());
+  immutable_worker_pool_params.emplace_back("RendererBackground",
+                                            ThreadPriority::BACKGROUND);
+  DCHECK_EQ(BACKGROUND_BLOCKING, immutable_worker_pool_params.size());
+  immutable_worker_pool_params.emplace_back("RendererBackgroundBlocking",
+                                            ThreadPriority::BACKGROUND);
+  DCHECK_EQ(FOREGROUND, immutable_worker_pool_params.size());
+  immutable_worker_pool_params.emplace_back("RendererForeground",
+                                            ThreadPriority::NORMAL);
+  DCHECK_EQ(FOREGROUND_BLOCKING, immutable_worker_pool_params.size());
+  immutable_worker_pool_params.emplace_back("RendererForegroundBlocking",
+                                            ThreadPriority::NORMAL);
+  return GetWorkerPoolParams(immutable_worker_pool_params,
+                             GetVariationParamsFromCommandLine(
+                                 *base::CommandLine::ForCurrentProcess()));
+}
+
+size_t RendererWorkerPoolIndexForTraits(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 task_scheduler_util