chrome: Cleanup class/struct forward declarations

chrome/browser/prefs/profile_pref_store_manager.h

 // Copyright 2014 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 CHROME_BROWSER_PREFS_PROFILE_PREF_STORE_MANAGER_H_
 #define CHROME_BROWSER_PREFS_PROFILE_PREF_STORE_MANAGER_H_
 
 #include <stddef.h>
 
 #include <memory>
@@ skipping 13 matching lines @@
 
 namespace base {
 class DictionaryValue;
 class SequencedTaskRunner;
 }  // namespace base
 
 namespace user_prefs {
 class PrefRegistrySyncable;
 }  // namespace user_prefs
 
-class PrefRegistrySimple;
-
 // Provides a facade through which the user preference store may be accessed and
 // managed.
 class ProfilePrefStoreManager {
  public:
   // Instantiates a ProfilePrefStoreManager with the configuration required to
   // manage the user preferences of the profile at |profile_path|.
   // |tracking_configuration| is used for preference tracking.
   // |reporting_ids_count| is the count of all possible tracked preference IDs
   // (possibly greater than |tracking_configuration.size()|).
   // |seed| and |device_id| are used to track preference value changes and must
@@ skipping 73 matching lines @@
       tracking_configuration_;
   const size_t reporting_ids_count_;
   const std::string seed_;
   const std::string device_id_;
   PrefService* local_state_;
 
   DISALLOW_COPY_AND_ASSIGN(ProfilePrefStoreManager);
 };
 
 #endif  // CHROME_BROWSER_PREFS_PROFILE_PREF_STORE_MANAGER_H_