Add support for the control group in the Simple Cache Experiment.

net/disk_cache/experiments.h

 // Copyright (c) 2011 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 NET_DISK_CACHE_EXPERIMENTS_H_
 #define NET_DISK_CACHE_EXPERIMENTS_H_
 
 
 namespace disk_cache {
 
 // This lists the experiment groups that we care about. Only add new groups at
 // the end of the list, and always increase the number.
 enum {
   NO_EXPERIMENT = 0,
   EXPERIMENT_OLD_FILE1 = 3,
   EXPERIMENT_OLD_FILE2 = 4,
   EXPERIMENT_DELETED_LIST_OUT = 11,
   EXPERIMENT_DELETED_LIST_CONTROL = 12,
   EXPERIMENT_DELETED_LIST_IN = 13,
-  EXPERIMENT_DELETED_LIST_OUT2 = 14
+  EXPERIMENT_DELETED_LIST_OUT2 = 14,
+  // There is no EXPERIMENT_SIMPLE_YES since this enum is used in the standard
+  // backend only.
+  EXPERIMENT_SIMPLE_CONTROL = 15,
 };
 
 }  // namespace disk_cache
 
 #endif  // NET_DISK_CACHE_EXPERIMENTS_H_