app_list: Another pass of cpplint.py to make it clean.

ui/app_list/views/folder_header_view_delegate.h

 // Copyright 2013 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 UI_APP_LIST_VIEWS_FOLDER_HEADER_VIEW_DELEGATE_H_
 #define UI_APP_LIST_VIEWS_FOLDER_HEADER_VIEW_DELEGATE_H_
 
+#include <string>
+
+namespace ui {
+class Event;
+}
+
 namespace app_list {
 
 class AppListFolderItem;
 
 class FolderHeaderViewDelegate {
  public:
   // Invoked when the back button on the folder header view is clicked.
   // |item| is the folder item which FolderHeaderview represents.
   // |event_flags| contains the flags of the keyboard/mouse event that triggers
   // the request.
   virtual void NavigateBack(AppListFolderItem* item,
                             const ui::Event& event_flags) = 0;
 
   // Gives back the focus to the search box.
   virtual void GiveBackFocusToSearchBox() = 0;
 
   // Tells the model to set the name of |item|.
   virtual void SetItemName(AppListFolderItem* item,
                            const std::string& name) = 0;
 
   virtual ~FolderHeaderViewDelegate() {}
 };
 
 }  // namespace app_list
 
 #endif  // UI_APP_LIST_VIEWS_FOLDER_HEADER_VIEW_DELEGATE_H_