chrome: Cleanup class/struct forward declarations

chrome/browser/extensions/api/settings_private/settings_private_event_router.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 CHROME_BROWSER_EXTENSIONS_API_SETTINGS_PRIVATE_SETTINGS_PRIVATE_EVENT_ROUTER_H_
 #define CHROME_BROWSER_EXTENSIONS_API_SETTINGS_PRIVATE_SETTINGS_PRIVATE_EVENT_ROUTER_H_
 
 #include <memory>
 
 #include "base/macros.h"
 #include "chrome/browser/chromeos/settings/cros_settings.h"
 #include "chrome/browser/extensions/api/settings_private/prefs_util.h"
 #include "components/keyed_service/core/keyed_service.h"
 #include "components/prefs/pref_change_registrar.h"
 #include "extensions/browser/event_router.h"
 
 namespace content {
 class BrowserContext;
 }
 
 namespace extensions {
 
-class SettingsPrivateDelegate;
-
 // This is an event router that will observe listeners to pref changes on the
 // appropriate pref service(s) and notify listeners on the JavaScript
 // settingsPrivate API.
 class SettingsPrivateEventRouter : public KeyedService,
                                    public EventRouter::Observer {
  public:
   static SettingsPrivateEventRouter* Create(
       content::BrowserContext* browser_context);
   ~SettingsPrivateEventRouter() override;
 
@@ skipping 33 matching lines @@
   bool listening_;
 
   std::unique_ptr<PrefsUtil> prefs_util_;
 
   DISALLOW_COPY_AND_ASSIGN(SettingsPrivateEventRouter);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_API_SETTINGS_PRIVATE_SETTINGS_PRIVATE_EVENT_ROUTER_H_