chrome: Cleanup class/struct forward declarations

chrome/browser/extensions/api/automation_internal/automation_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_AUTOMATION_INTERNAL_AUTOMATION_EVENT_ROUTER_H_
 #define CHROME_BROWSER_EXTENSIONS_API_AUTOMATION_INTERNAL_AUTOMATION_EVENT_ROUTER_H_
 
 #include <set>
 #include <vector>
 
 #include "base/macros.h"
 #include "base/memory/singleton.h"
 #include "chrome/common/extensions/api/automation_internal.h"
 #include "content/public/browser/ax_event_notification_details.h"
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
 #include "extensions/common/extension_id.h"
 
 class Profile;
 
 namespace content {
 class BrowserContext;
 }  // namespace content
 
 struct ExtensionMsg_AccessibilityEventParams;
 struct ExtensionMsg_AccessibilityLocationChangeParams;
 
 namespace extensions {
 struct AutomationListener;
-class Extension;
 
 class AutomationEventRouter : public content::NotificationObserver {
  public:
   static AutomationEventRouter* GetInstance();
 
   // Indicates that the listener at |listener_process_id|, |listener_routing_id|
   // wants to receive automation events from the accessibility tree indicated
   // by |source_ax_tree_id|. Automation events are forwarded from now on
   // until the listener process dies.
   void RegisterListenerForOneTree(const ExtensionId& extension_id,
@@ skipping 67 matching lines @@
   Profile* active_profile_;
 
   friend struct base::DefaultSingletonTraits<AutomationEventRouter>;
 
   DISALLOW_COPY_AND_ASSIGN(AutomationEventRouter);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_API_AUTOMATION_INTERNAL_AUTOMATION_EVENT_ROUTER_H_