Store field trial parameters in shared memory

components/variations/variations_seed_processor.cc

 // Copyright 2013 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.
 
 #include "components/variations/variations_seed_processor.h"
 
 #include <stddef.h>
 
 #include <map>
 #include <vector>
@@ skipping 68 matching lines @@
 
 // Forces the specified |experiment| to be enabled in |study|.
 void ForceExperimentState(
     const Study& study,
     const Study_Experiment& experiment,
     const VariationsSeedProcessor::UIStringOverrideCallback& override_callback,
     base::FieldTrial* trial) {
   RegisterExperimentParams(study, experiment);
   RegisterVariationIds(experiment, study.name());
   if (study.activation_type() == Study_ActivationType_ACTIVATION_AUTO) {
+    // This call must happen after all params have been registered for the
+    // trial. Otherwise, since we look up params by trial and group name, the
+    // params won't be registered under the correct key.
     trial->group();
     // UI Strings can only be overridden from ACTIVATION_AUTO experiments.
     ApplyUIStringOverrides(experiment, override_callback);
   }
 }
 
 // Registers feature overrides for the chosen experiment in the specified study.
 void RegisterFeatureOverrides(const ProcessedStudy& processed_study,
                               base::FieldTrial* trial,
                               base::FeatureList* feature_list) {
@@ skipping 204 matching lines @@
   }
 
   trial->SetForced();
   if (processed_study.is_expired())
     trial->Disable();
 
   if (enables_or_disables_features)
     RegisterFeatureOverrides(processed_study, trial.get(), feature_list);
 
   if (study.activation_type() == Study_ActivationType_ACTIVATION_AUTO) {
+    // This call must happen after all params have been registered for the
+    // trial. Otherwise, since we look up params by trial and group name, the
+    // params won't be registered under the correct key.
     const std::string& group_name = trial->group_name();
 
     // Don't try to apply overrides if none of the experiments in this study had
     // any.
     if (!has_overrides)
       return;
 
     // UI Strings can only be overridden from ACTIVATION_AUTO experiments.
     int experiment_index = processed_study.GetExperimentIndexByName(group_name);
 
     // The field trial was defined from |study|, so the active experiment's name
     // must be in the |study|.
     DCHECK_NE(-1, experiment_index);
 
     ApplyUIStringOverrides(study.experiment(experiment_index),
                            override_callback);
   }
 }
 
 }  // namespace variations