Allow trials to associate without overriding a feature.

components/variations/processed_study.h

 // 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.
 
 #ifndef COMPONENTS_VARIATIONS_PROCESSED_STUDY_H_
 #define COMPONENTS_VARIATIONS_PROCESSED_STUDY_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 17 matching lines @@
   base::FieldTrial::Probability total_probability() const {
     return total_probability_;
   }
 
   bool all_assignments_to_one_group() const {
     return all_assignments_to_one_group_;
   }
 
   bool is_expired() const { return is_expired_; }
 
+  const std::string& single_feature_name() const {
+    return single_feature_name_;
+  }
+
   // Gets the index of the experiment with the given |name|. Returns -1 if no
   // experiment is found.
   int GetExperimentIndexByName(const std::string& name) const;
 
   static bool ValidateAndAppendStudy(
       const Study* study,
       bool is_expired,
       std::vector<ProcessedStudy>* processed_studies);
 
  private:
   // Corresponding Study object. Weak reference.
   const Study* study_;
 
   // Computed total group probability for the study.
   base::FieldTrial::Probability total_probability_;
 
   // Whether all assignments are to a single group.
   bool all_assignments_to_one_group_;
 
   // Whether the study is expired.
   bool is_expired_;
+
+  // If the study has groups that enable/disable a single feature, the name of
+  // that feature.
+  std::string single_feature_name_;
 };
 
 }  // namespace variations
 
 #endif  // COMPONENTS_VARIATIONS_PROCESSED_STUDY_H_