components: Cleanup class/struct fwd declarations

components/content_settings/core/browser/content_settings_pref.h

 // Copyright 2015 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_CONTENT_SETTINGS_CORE_BROWSER_CONTENT_SETTINGS_PREF_H_
 #define COMPONENTS_CONTENT_SETTINGS_CORE_BROWSER_CONTENT_SETTINGS_PREF_H_
 
 #include <stddef.h>
 
 #include <string>
 
 #include "base/callback.h"
 #include "base/macros.h"
 #include "base/synchronization/lock.h"
 #include "base/threading/thread_checker.h"
 #include "base/values.h"
 #include "components/content_settings/core/browser/content_settings_origin_identifier_value_map.h"
 #include "components/content_settings/core/browser/content_settings_provider.h"
 #include "components/content_settings/core/common/content_settings_pattern.h"
 #include "components/content_settings/core/common/content_settings_types.h"
 
 class PrefService;
 class PrefChangeRegistrar;
 
 namespace base {
 class Clock;
 class DictionaryValue;
 }
 
-namespace user_prefs {
-class PrefRegistrySyncable;
-}
-
 namespace content_settings {
 
 class RuleIterator;
 
 // Represents a single pref for reading/writing content settings of one type.
 class ContentSettingsPref {
  public:
   typedef base::Callback<void(const ContentSettingsPattern&,
                               const ContentSettingsPattern&,
                               ContentSettingsType,
@@ skipping 87 matching lines @@
   mutable base::Lock lock_;
 
   base::ThreadChecker thread_checker_;
 
   DISALLOW_COPY_AND_ASSIGN(ContentSettingsPref);
 };
 
 }  // namespace content_settings
 
 #endif  // COMPONENTS_CONTENT_SETTINGS_CORE_BROWSER_CONTENT_SETTINGS_PREF_H_