Make VariationsService simulate received seeds.

base/metrics/field_trial.h

 // Copyright (c) 2012 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 425 matching lines @@
 
   // Remove an observer.
   static void RemoveObserver(Observer* observer);
 
   // Notify all observers that a group has been finalized for |field_trial|.
   static void NotifyFieldTrialGroupSelection(FieldTrial* field_trial);
 
   // Return the number of active field trials.
   static size_t GetFieldTrialCount();
 
+  // If one-time randomization is enabled, returns a weak pointer to the
+  // corresponding EntropyProvider. Otherwise, returns NULL. The returned
+  // entropy provider is owned by the global FieldTrialList and is guaranteed to
+  // remain valid until the global FieldTrialList is destroyed.
+  static const FieldTrial::EntropyProvider*
+      GetEntropyProviderForOneTimeRandomization();
+
  private:
   // A map from FieldTrial names to the actual instances.
   typedef std::map<std::string, FieldTrial*> RegistrationMap;
 
-  // If one-time randomization is enabled, returns a weak pointer to the
-  // corresponding EntropyProvider. Otherwise, returns NULL.
-  static const FieldTrial::EntropyProvider*
-      GetEntropyProviderForOneTimeRandomization();
-
   // Helper function should be called only while holding lock_.
   FieldTrial* PreLockedFind(const std::string& name);
 
   // Register() stores a pointer to the given trial in a global map.
   // This method also AddRef's the indicated trial.
   // This should always be called after creating a new FieldTrial instance.
   static void Register(FieldTrial* trial);
 
   static FieldTrialList* global_;  // The singleton of this class.
 
@@ skipping 13 matching lines @@
 
   // List of observers to be notified when a group is selected for a FieldTrial.
   scoped_refptr<ObserverListThreadSafe<Observer> > observer_list_;
 
   DISALLOW_COPY_AND_ASSIGN(FieldTrialList);
 };
 
 }  // namespace base
 
 #endif  // BASE_METRICS_FIELD_TRIAL_H_