Introduce a new FieldTrialList::IsTrialActive() API.

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 378 matching lines @@
       const std::string& trial_name,
       FieldTrial::Probability total_probability,
       const std::string& default_group_name,
       const int year,
       const int month,
       const int day_of_month,
       FieldTrial::RandomizationType randomization_type,
       uint32 randomization_seed,
       int* default_group_number);
 
-  // The Find() method can be used to test to see if a named Trial was already
+  // The Find() method can be used to test to see if a named trial was already
   // registered, or to retrieve a pointer to it from the global map.
-  static FieldTrial* Find(const std::string& name);
+  static FieldTrial* Find(const std::string& trial_name);
 
   // Returns the group number chosen for the named trial, or
   // FieldTrial::kNotFinalized if the trial does not exist.
-  static int FindValue(const std::string& name);
+  static int FindValue(const std::string& trial_name);
 
   // Returns the group name chosen for the named trial, or the empty string if
   // the trial does not exist. The first call of this function on a given field
   // trial will mark it as active, so that its state will be reported with usage
   // metrics, crashes, etc.
-  static std::string FindFullName(const std::string& name);
+  static std::string FindFullName(const std::string& trial_name);
 
   // Returns true if the named trial has been registered.
-  static bool TrialExists(const std::string& name);
+  static bool TrialExists(const std::string& trial_name);
+
+  // Returns true if the named trial exists and has been activated.
+  static bool IsTrialActive(const std::string& trial_name);
 
   // Creates a persistent representation of active FieldTrial instances for
   // resurrection in another process. This allows randomization to be done in
   // one process, and secondary processes can be synchronized on the result.
   // The resulting string contains the name and group name pairs of all
   // registered FieldTrials for which the group has been chosen and externally
   // observed (via |group()|) and which have not been disabled, with "/" used
   // to separate all names and to terminate the string. This string is parsed
   // by |CreateTrialsFromString()|.
   static void StatesToString(std::string* output);
@@ skipping 88 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_