Add back a check for improper usage of IsOneTimeRandomizationEnabled.

base/metrics/field_trial.h

 // Copyright (c) 2011 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.
 
 // FieldTrial is a class for handling details of statistical experiments
 // performed by actual users in the field (i.e., in a shipped or beta product).
 // All code is called exclusively on the UI thread currently.
 //
 // The simplest example is an experiment to see whether one of two options
 // produces "better" results across our user population.  In that scenario, UMA
@@ skipping 346 matching lines @@
 
  private:
   // A map from FieldTrial names to the actual instances.
   typedef std::map<std::string, FieldTrial*> RegistrationList;
 
   // Helper function should be called only while holding lock_.
   FieldTrial* PreLockedFind(const std::string& name);
 
   static FieldTrialList* global_;  // The singleton of this class.
 
-  // This will tell us if there is an attempt to register a field trial without
-  // creating the FieldTrialList. This is not an error, unless a FieldTrialList
-  // is created after that.
-  static bool register_without_global_;
+  // This will tell us if there is an attempt to register a field
+  // trial or check if one-time randomization is enabled without
+  // creating the FieldTrialList. This is not an error, unless a
+  // FieldTrialList is created after that.
+  static bool used_without_global_;
 
   // A helper value made available to users, that shows when the FieldTrialList
   // was initialized.  Note that this is a singleton instance, and hence is a
   // good approximation to the start of the process.
   TimeTicks application_start_time_;
 
   // Lock for access to registered_.
   base::Lock lock_;
   RegistrationList registered_;
 
   // An opaque, diverse ID for this client that does not change
   // between sessions, or the empty string if not initialized.
   std::string client_id_;
 
   // List of observers to be notified when a group is selected for a FieldTrial.
   ObserverList<Observer> observer_list_;
 
   DISALLOW_COPY_AND_ASSIGN(FieldTrialList);
 };
 
 }  // namespace base
 
 #endif  // BASE_METRICS_FIELD_TRIAL_H_