Make it so disabled field trials are not reported as active.

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 199 matching lines @@
   // Sets the group_name as well as group_name_hash to make sure they are sync.
   void SetGroupChoice(const std::string& name, int number);
 
   // Ensures that a group is chosen, if it hasn't yet been. The field trial
   // might yet be disabled, so this call will *not* notify observers of the
   // status.
   void FinalizeGroupChoice();
 
   // Returns the trial name and selected group name for this field trial via
   // the output parameter |active_group|, but only if the group has already
-  // been chosen and has been externally observed via |group()|. In that case,
-  // true is returned and |active_group| is filled in; otherwise, the result
-  // is false and |active_group| is left untouched.
+  // been chosen and has been externally observed via |group()| and the trial
+  // has not been disabled. In that case, true is returned and |active_group|
+  // is filled in; otherwise, the result is false and |active_group| is left
+  // untouched.
   bool GetActiveGroup(ActiveGroup* active_group) const;
 
   // Returns the group_name. A winner need not have been chosen.
   std::string group_name_internal() const { return group_name_; }
 
   // The name of the field trial, as can be found via the FieldTrialList.
   const std::string name_;
 
   // The maximum sum of all probabilities supplied, which corresponds to 100%.
   // This is the scaling factor used to adjust supplied probabilities.
@@ skipping 115 matching lines @@
   static std::string FindFullName(const std::string& name);
 
   // Returns true if the named trial has been registered.
   static bool TrialExists(const std::string& 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()|), with "/" used to separate all names and to
-  // terminate the string. This string is parsed by |CreateTrialsFromString()|.
+  // 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);
 
   // Fills in the supplied vector |active_groups| (which must be empty when
   // called) with a snapshot of all registered FieldTrials for which the group
-  // has been chosen and externally observed (via |group()|).
+  // has been chosen and externally observed (via |group()|) and which have
+  // not been disabled.
   static void GetActiveFieldTrialGroups(
       FieldTrial::ActiveGroups* active_groups);
 
   // Use a state string (re: StatesToString()) to augment the current list of
   // field tests to include the supplied tests, and using a 100% probability for
   // each test, force them to have the same group string.  This is commonly used
   // in a non-browser process, to carry randomly selected state in a browser
   // process into this non-browser process, but could also be invoked through a
   // command line argument to the browser process.
   static bool CreateTrialsFromString(const std::string& prior_trials);
@@ skipping 57 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_