scheduler: Always create a real scheduler in unit tests

components/scheduler/BUILD.gn

 # Copyright 2015 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.
 
 import("//components/scheduler/scheduler.gni")
 
 # GYP version: components/scheduler.gypi:scheduler
 component("scheduler") {
   sources = rebase_path(scheduler_gypi_values.scheduler_sources,
                         ".",
@@ skipping 42 matching lines @@
     "renderer/webthread_impl_for_renderer_scheduler_unittest.cc",
   ]
 
   deps = [
     ":scheduler",
     "//cc:test_support",
     "//testing/gmock",
     "//testing/gtest",
   ]
 }
+
+# GYP version: components/scheduler.gypi:scheduler_test_support
+static_library("test_support") {
+  sources = rebase_path(scheduler_gypi_values.scheduler_test_support_sources,
+                        ".",
+                        "//components/scheduler")
+
+  deps = [
+    "//base",
+  ]
+}