chrome: Cleanup class/struct forward declarations

chrome/browser/notifications/arc_application_notifier_source_chromeos.h

 // Copyright 2016 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_NOTIFICATIONS_ARC_APPLICATION_NOTIFIER_SOURCE_CHROMEOS_H_
 #define CHROME_BROWSER_NOTIFICATIONS_ARC_APPLICATION_NOTIFIER_SOURCE_CHROMEOS_H_
 
 #include <map>
 #include <memory>
 #include <string>
 #include <vector>
 
 #include "base/macros.h"
 #include "chrome/browser/notifications/notifier_source.h"
 #include "chrome/browser/ui/app_list/arc/arc_app_icon.h"
 #include "chrome/browser/ui/app_list/arc/arc_app_list_prefs.h"
 
 class Profile;
 
-namespace content {
-class BrowserContext;
-}
-
 namespace message_center {
 struct Notifier;
 }
 
 namespace arc {
 
 // TODO(hirono): Observe enabled flag change and notify it to message center.
 class ArcApplicationNotifierSourceChromeOS : public NotifierSource,
                                              public ArcAppIcon::Observer,
                                              public ArcAppListPrefs::Observer {
@@ skipping 23 matching lines @@
 
   NotifierSource::Observer* observer_;
   std::vector<std::unique_ptr<ArcAppIcon>> icons_;
   std::map<std::string, std::string> package_to_app_ids_;
   Profile* last_profile_;
 };
 
 }  // namespace arc
 
 #endif  // CHROME_BROWSER_NOTIFICATIONS_ARC_APPLICATION_NOTIFIER_SOURCE_CHROMEOS_H_