Revert of Supporting study definitions without default groups and end_date filtering.

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>
 
 #include "base/metrics/field_trial.h"
 
 namespace variations {
 
 class Study;
 
 // Wrapper over Study with extra information computed during pre-processing,
 // such as whether the study is expired and its total probability.
 class ProcessedStudy {
  public:
-  // The default group used when a study doesn't specify one. This is needed
-  // because the field trial api requires a default group name.
-  static const std::string kGenericDefaultExperimentName;
-
   ProcessedStudy();
   ~ProcessedStudy();
 
   bool Init(const Study* study, bool is_expired);
 
   const Study* study() const { return study_; }
 
   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;
 
-  // Gets the default experiment name for the study, or a generic one if none is
-  // specified.
-  const std::string& GetDefaultExperimentName() 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_