Make VariationsService simulate received seeds.

base/metrics/field_trial.h

Index: base/metrics/field_trial.h
===================================================================
--- base/metrics/field_trial.h	(revision 265923)
+++ base/metrics/field_trial.h	(working copy)
@@ -443,15 +443,17 @@
   // 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);