chrome: Cleanup class/struct forward declarations

chrome/browser/extensions/updater/extension_updater.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 CHROME_BROWSER_EXTENSIONS_UPDATER_EXTENSION_UPDATER_H_
 #define CHROME_BROWSER_EXTENSIONS_UPDATER_EXTENSION_UPDATER_H_
 
 #include <list>
 #include <map>
 #include <memory>
@@ skipping 14 matching lines @@
 #include "extensions/browser/extension_registry_observer.h"
 #include "extensions/browser/updater/extension_downloader.h"
 #include "extensions/browser/updater/extension_downloader_delegate.h"
 #include "extensions/browser/updater/manifest_fetch_data.h"
 #include "url/gurl.h"
 
 class ExtensionServiceInterface;
 class PrefService;
 class Profile;
 
-namespace content {
-class BrowserContext;
-}
-
 namespace extensions {
 
 class ExtensionCache;
 class ExtensionPrefs;
-class ExtensionRegistry;
 class ExtensionSet;
 class ExtensionUpdaterTest;
 
 // A class for doing auto-updates of installed Extensions. Used like this:
 //
 // ExtensionUpdater* updater = new ExtensionUpdater(my_extensions_service,
 //                                                  extension_prefs,
 //                                                  pref_service,
 //                                                  profile,
 //                                                  update_frequency_secs,
@@ skipping 202 matching lines @@
   ExtensionCache* extension_cache_;
 
   base::WeakPtrFactory<ExtensionUpdater> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ExtensionUpdater);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_UPDATER_EXTENSION_UPDATER_H_