Send all field trials from the browser.

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 88 matching lines @@
     virtual double GetEntropyForTrial(const std::string& trial_name,
                                       uint32 randomization_seed) const = 0;
   };
 
   // A pair representing a Field Trial and its selected group.
   struct ActiveGroup {
     std::string trial_name;
     std::string group_name;
   };
 
+  // A triplet representing a Field Trial, its selected group and whether it's
+  // active.
+  struct AllGroup {

[Alexei Svitkine (slow), 2014/11/05 16:17:13]

AllGroup is a weird name.

How about FieldTrialState?

+    std::string trial_name;
+    std::string group_name;
+    bool activated;
+  };
+
   typedef std::vector<ActiveGroup> ActiveGroups;
+  typedef std::vector<AllGroup> AllGroups;
 
   // A return value to indicate that a given instance has not yet had a group
   // assignment (and hence is not yet participating in the trial).
   static const int kNotFinalized;
 
   // Disables this trial, meaning it always determines the default group
   // has been selected. May be called immediately after construction, or
   // at any time after initialization (should not be interleaved with
   // AppendGroup calls). Once disabled, there is no way to re-enable a
   // trial.
@@ skipping 53 matching lines @@
  private:
   // Allow tests to access our innards for testing purposes.
   FRIEND_TEST_ALL_PREFIXES(FieldTrialTest, Registration);
   FRIEND_TEST_ALL_PREFIXES(FieldTrialTest, AbsoluteProbabilities);
   FRIEND_TEST_ALL_PREFIXES(FieldTrialTest, RemainingProbability);
   FRIEND_TEST_ALL_PREFIXES(FieldTrialTest, FiftyFiftyProbability);
   FRIEND_TEST_ALL_PREFIXES(FieldTrialTest, MiddleProbabilities);
   FRIEND_TEST_ALL_PREFIXES(FieldTrialTest, OneWinner);
   FRIEND_TEST_ALL_PREFIXES(FieldTrialTest, DisableProbability);
   FRIEND_TEST_ALL_PREFIXES(FieldTrialTest, ActiveGroups);
+  FRIEND_TEST_ALL_PREFIXES(FieldTrialTest, AllGroups);
   FRIEND_TEST_ALL_PREFIXES(FieldTrialTest, ActiveGroupsNotFinalized);
   FRIEND_TEST_ALL_PREFIXES(FieldTrialTest, Save);
   FRIEND_TEST_ALL_PREFIXES(FieldTrialTest, DuplicateRestore);
   FRIEND_TEST_ALL_PREFIXES(FieldTrialTest, SetForcedTurnFeatureOff);
   FRIEND_TEST_ALL_PREFIXES(FieldTrialTest, SetForcedTurnFeatureOn);
   FRIEND_TEST_ALL_PREFIXES(FieldTrialTest, SetForcedChangeDefault_Default);
   FRIEND_TEST_ALL_PREFIXES(FieldTrialTest, SetForcedChangeDefault_NonDefault);
   FRIEND_TEST_ALL_PREFIXES(FieldTrialTest, FloatBoundariesGiveEqualGroupSizes);
   FRIEND_TEST_ALL_PREFIXES(FieldTrialTest, DoesNotSurpassTotalProbability);
 
@@ skipping 30 matching lines @@
   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()| 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 trial name and selected group name for this field trial via
+  // the output parameter |all_group|, but only if  the trial
+  // has not been disabled. In that case, true is returned and |all_group|
+  // is filled in; otherwise, the result is false and |all_group| is left
+  // untouched.
+  bool GetAllGroup(AllGroup* all_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 trial_name_;
 
   // The maximum sum of all probabilities supplied, which corresponds to 100%.
   // This is the scaling factor used to adjust supplied probabilities.
   const Probability divisor_;
 
@@ skipping 154 matching lines @@
   // 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);
 
+  // Creates a persistent representation of all 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 which have not been disabled, with "/" used
+  // to separate all names and to terminate the string. All activated trials
+  // have their name prefixed with "*". This string is parsed by
+  // |CreateTrialsFromString()|.
+  static void AllStatesToString(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()|) and which have
   // not been disabled.
   static void GetActiveFieldTrialGroups(
       FieldTrial::ActiveGroups* active_groups);
 
+  // Fills in the supplied vector |all_groups| (which must be empty when called)
+  // with a snapshot of all registered FieldTrials which have not been disabled.
+  static void GetAllFieldTrialGroups(

[Alexei Svitkine (slow), 2014/11/05 16:17:14]

Does this need to be public?

[Georges Khalil, 2014/11/05 20:00:12]

No, moved it to private.

+      FieldTrial::AllGroups* all_groups);
+
   // Use a state string (re: StatesToString()) to augment the current list of
   // field trials to include the supplied trials, and using a 100% probability
   // for each trial, 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. The created field
   // trials are all marked as "used" for the purposes of active trial reporting
   // if |mode| is ACTIVATE_TRIALS, otherwise each trial will be marked as "used"
   // if it is prefixed with |kActivationMarker|. Trial names in
   // |ignored_trial_names| are ignored when parsing |prior_trials|.
@@ skipping 60 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_