chrome: Cleanup class/struct forward declarations

chrome/browser/download/download_shelf_context_menu.h

 // Copyright (c) 2011 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_DOWNLOAD_DOWNLOAD_SHELF_CONTEXT_MENU_H_
 #define CHROME_BROWSER_DOWNLOAD_DOWNLOAD_SHELF_CONTEXT_MENU_H_
 
 #include <memory>
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "base/strings/string16.h"
 #include "build/build_config.h"
 #include "chrome/browser/download/download_commands.h"
 #include "content/public/browser/download_item.h"
 #include "ui/base/models/simple_menu_model.h"
 
-namespace content {
-class PageNavigator;
-}
-
 // This class is responsible for the download shelf context menu. Platform
 // specific subclasses are responsible for creating and running the menu.
 //
 // The DownloadItem corresponding to the context menu is observed for removal or
 // destruction.
 class DownloadShelfContextMenu : public ui::SimpleMenuModel::Delegate,
                                  public content::DownloadItem::Observer {
  public:
   ~DownloadShelfContextMenu() override;
 
@@ skipping 39 matching lines @@
   std::unique_ptr<ui::SimpleMenuModel> malicious_download_menu_model_;
 
   // Information source.
   content::DownloadItem* download_item_;
   std::unique_ptr<DownloadCommands> download_commands_;
 
   DISALLOW_COPY_AND_ASSIGN(DownloadShelfContextMenu);
 };
 
 #endif  // CHROME_BROWSER_DOWNLOAD_DOWNLOAD_SHELF_CONTEXT_MENU_H_