chrome: Cleanup class/struct forward declarations

chrome/browser/ui/webui/signin/sync_confirmation_handler.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_UI_WEBUI_SIGNIN_SYNC_CONFIRMATION_HANDLER_H_
 #define CHROME_BROWSER_UI_WEBUI_SIGNIN_SYNC_CONFIRMATION_HANDLER_H_
 
 #include <string>
 
 #include "base/macros.h"
 #include "chrome/browser/ui/webui/signin/login_ui_service.h"
 #include "components/signin/core/browser/account_tracker_service.h"
 #include "content/public/browser/web_ui_message_handler.h"
 
-class Browser;
-
 namespace base {
 class ListValue;
 }
 
 class SyncConfirmationHandler : public content::WebUIMessageHandler,
                                 public AccountTrackerService::Observer {
  public:
   SyncConfirmationHandler();
   ~SyncConfirmationHandler() override;
 
@@ skipping 35 matching lines @@
       LoginUIService::SyncConfirmationUIClosedResult result);
 
  private:
   // Records whether the user clicked on Undo, Ok, or Settings.
   bool did_user_explicitly_interact;
 
   DISALLOW_COPY_AND_ASSIGN(SyncConfirmationHandler);
 };
 
 #endif  // CHROME_BROWSER_UI_WEBUI_SIGNIN_SYNC_CONFIRMATION_HANDLER_H_