Control TaskScheduler initialization params in renderers via field trial.

components/task_scheduler_util/renderer/initialization.cc

Index: components/task_scheduler_util/renderer/initialization.cc
diff --git a/components/task_scheduler_util/renderer/initialization.cc b/components/task_scheduler_util/renderer/initialization.cc
new file mode 100644
index 0000000000000000000000000000000000000000..bf17fe13d16ac4c819e5891c90aa74a1a001e568
--- /dev/null
+++ b/components/task_scheduler_util/renderer/initialization.cc
@@ -0,0 +1,58 @@
+// 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.
+
+#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_FILE_IO,
+  FOREGROUND,
+  FOREGROUND_FILE_IO,
+  WORKER_POOL_COUNT  // Always last.
+};
+
+}  // namespace
+
+std::vector<base::SchedulerWorkerPoolParams> GetRendererWorkerPoolParams() {
+  using ThreadPriority = base::ThreadPriority;
+  std::vector<SchedulerConstantWorkerPoolParams> constant_worker_pool_params;
+  DCHECK_EQ(BACKGROUND, constant_worker_pool_params.size());
+  constant_worker_pool_params.emplace_back("RendererBackground",
+                                           ThreadPriority::BACKGROUND);
+  DCHECK_EQ(BACKGROUND_FILE_IO, constant_worker_pool_params.size());
+  constant_worker_pool_params.emplace_back("RendererBackgroundFileIO",
+                                           ThreadPriority::BACKGROUND);
+  DCHECK_EQ(FOREGROUND, constant_worker_pool_params.size());
+  constant_worker_pool_params.emplace_back("RendererForeground",
+                                           ThreadPriority::NORMAL);
+  DCHECK_EQ(FOREGROUND_FILE_IO, constant_worker_pool_params.size());
+  constant_worker_pool_params.emplace_back("RendererForegroundFileIO",
+                                           ThreadPriority::NORMAL);
+  return GetWorkerPoolParams(constant_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.with_file_io())
+    return is_background ? BACKGROUND_FILE_IO : FOREGROUND_FILE_IO;
+  return is_background ? BACKGROUND : FOREGROUND;
+}
+
+}  // namespace task_scheduler_util