chrome: Cleanup class/struct forward declarations

chrome/browser/ui/app_list/extension_app_model_builder.h

 // Copyright 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 CHROME_BROWSER_UI_APP_LIST_EXTENSION_APP_MODEL_BUILDER_H_
 #define CHROME_BROWSER_UI_APP_LIST_EXTENSION_APP_MODEL_BUILDER_H_
 
 #include <stddef.h>
 
 #include <memory>
 #include <string>
 #include <vector>
 
 #include "base/macros.h"
 #include "chrome/browser/extensions/install_observer.h"
 #include "chrome/browser/ui/app_list/app_list_model_builder.h"
 #include "chrome/browser/ui/ash/launcher/launcher_app_updater.h"
 #include "components/prefs/pref_change_registrar.h"
 #include "ui/base/models/list_model_observer.h"
 
 class AppListControllerDelegate;
 class LauncherExtensionAppUpdater;
 class ExtensionAppItem;
 
 namespace extensions {
 class Extension;
-class ExtensionRegistry;
-class ExtensionSet;
 class InstallTracker;
 }
 
 namespace gfx {
 class ImageSkia;
 }
 
 // This class populates and maintains the given |model| for extension items
 // with information from |profile|.
 class ExtensionAppModelBuilder : public AppListModelBuilder,
@@ skipping 59 matching lines @@
   // We listen to this to show app installing progress.
   extensions::InstallTracker* tracker_ = nullptr;
 
   // Dispatches extension lifecycle events.
   std::unique_ptr<LauncherExtensionAppUpdater> app_updater_;
 
   DISALLOW_COPY_AND_ASSIGN(ExtensionAppModelBuilder);
 };
 
 #endif  // CHROME_BROWSER_UI_APP_LIST_EXTENSION_APP_MODEL_BUILDER_H_