components: Cleanup class/struct fwd declarations

components/sync_preferences/testing_pref_service_syncable.h

 // Copyright (c) 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_SYNC_PREFERENCES_TESTING_PREF_SERVICE_SYNCABLE_H_
 #define COMPONENTS_SYNC_PREFERENCES_TESTING_PREF_SERVICE_SYNCABLE_H_
 
 #include "base/macros.h"
 #include "components/prefs/testing_pref_service.h"
 #include "components/sync_preferences/pref_service_syncable.h"
 
 namespace user_prefs {
 class PrefRegistrySyncable;
 }
 
 namespace sync_preferences {
 
-class PrefModelAssociatorClient;
-
 // Test version of PrefServiceSyncable.
 class TestingPrefServiceSyncable
     : public TestingPrefServiceBase<PrefServiceSyncable,
                                     user_prefs::PrefRegistrySyncable> {
  public:
   TestingPrefServiceSyncable();
   TestingPrefServiceSyncable(TestingPrefStore* managed_prefs,
                              TestingPrefStore* user_prefs,
                              TestingPrefStore* recommended_prefs,
                              user_prefs::PrefRegistrySyncable* pref_registry,
@@ skipping 16 matching lines @@
 template <>
 TestingPrefServiceBase<sync_preferences::PrefServiceSyncable,
                        user_prefs::PrefRegistrySyncable>::
     TestingPrefServiceBase(TestingPrefStore* managed_prefs,
                            TestingPrefStore* user_prefs,
                            TestingPrefStore* recommended_prefs,
                            user_prefs::PrefRegistrySyncable* pref_registry,
                            PrefNotifierImpl* pref_notifier);
 
 #endif  // COMPONENTS_SYNC_PREFERENCES_TESTING_PREF_SERVICE_SYNCABLE_H_