Control TaskScheduler initialization params in renderers via field trial.

components/task_scheduler_util/renderer/BUILD.gn

Index: components/task_scheduler_util/renderer/BUILD.gn
diff --git a/components/task_scheduler_util/renderer/BUILD.gn b/components/task_scheduler_util/renderer/BUILD.gn
new file mode 100644
index 0000000000000000000000000000000000000000..473fcd24bce5ddb7f064f2b6f030c821c8998c71
--- /dev/null
+++ b/components/task_scheduler_util/renderer/BUILD.gn
@@ -0,0 +1,17 @@
+# 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.
+
+if (!is_ios) {
+  static_library("renderer") {
+    sources = [
+      "initialization.cc",
+      "initialization.h",
+    ]
+
+    deps = [
+      "//base",
+      "//components/task_scheduler_util/common",
+    ]
+  }
+}