Update NetworkTimeQueries field trial config

components/network_time/network_time_test_utils.h

 // 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.
 
 #ifndef COMPONENTS_NETWORK_TIME_NETWORK_TIME_TEST_UTILS_H_
 #define COMPONENTS_NETWORK_TIME_NETWORK_TIME_TEST_UTILS_H_
 
 #include <map>
 #include <memory>
 
@@ skipping 32 matching lines @@
 
 // The time that |kGoodTimeResponseBody| uses. Can be converted to a
 // base::Time with base::Time::FromJsTime.
 extern const double kGoodTimeResponseHandlerJsTime;
 
 // Returns a valid network time response using the constants above. See
 // comments in the .cc for how to update the time returned in the response.
 std::unique_ptr<net::test_server::HttpResponse> GoodTimeResponseHandler(
     const net::test_server::HttpRequest& request);
 
-// Allows tests to configure the network time queries field trial.
+// Allows unit tests to configure the network time queries field trial.
 class FieldTrialTest {
  public:
+  FieldTrialTest();
   virtual ~FieldTrialTest();
 
-  // A FieldTrialList exists as a global singleton. Use
-  // CreateForUnitTest() in unit tests to create a FieldTrialTest that
-  // creates its own FieldTrialList; use CreateForBrowserTest() to use
-  // the singleton FieldTrialList that is created during browser setup.
-  static FieldTrialTest* CreateForUnitTest();
-  static FieldTrialTest* CreateForBrowserTest();
-
   void SetNetworkQueriesWithVariationsService(
       bool enable,
       float query_probability,
       NetworkTimeTracker::FetchBehavior fetch_behavior);
 
  private:
-  FieldTrialTest();
-  bool create_field_trial_list_ = true;
   std::unique_ptr<base::FieldTrialList> field_trial_list_;
   std::unique_ptr<base::test::ScopedFeatureList> scoped_feature_list_;
 
   DISALLOW_COPY_AND_ASSIGN(FieldTrialTest);
 };
 
 }  // namespace network_time
 
 #endif  // COMPONENTS_NETWORK_TIME_NETWORK_TIME_TEST_UTILS_H_