components: Cleanup class/struct fwd declarations

components/sync/base/sync_prefs.h

 // Copyright (c) 2012 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_SYNC_BASE_SYNC_PREFS_H_
 #define COMPONENTS_SYNC_BASE_SYNC_PREFS_H_
 
 #include <stdint.h>
 
 #include <map>
 #include <memory>
 #include <string>
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "base/observer_list.h"
 #include "base/threading/non_thread_safe.h"
 #include "base/time/time.h"
 #include "build/build_config.h"
 #include "components/prefs/pref_member.h"
 #include "components/sync/base/model_type.h"
 #include "components/sync/protocol/sync.pb.h"
 
 class PrefService;
-class ProfileIOData;
 
 namespace user_prefs {
 class PrefRegistrySyncable;
 }
 
 namespace syncer {
 
 class SyncPrefObserver {
  public:
   // Called whenever the pref that controls whether sync is managed
@@ skipping 179 matching lines @@
   // etc.
   typedef std::map<ModelType, ModelTypeSet> PrefGroupsMap;
   PrefGroupsMap pref_groups_;
 
   DISALLOW_COPY_AND_ASSIGN(SyncPrefs);
 };
 
 }  // namespace syncer
 
 #endif  // COMPONENTS_SYNC_BASE_SYNC_PREFS_H_