Add missing include guards in Cocoa code.

chrome/browser/ui/cocoa/download/download_shelf_context_menu_controller.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 CHROME_BROWSER_UI_COCOA_DOWNLOAD_DOWNLOAD_SHELF_CONTEXT_MENU_CONTROLLER_H_
+#define CHROME_BROWSER_UI_COCOA_DOWNLOAD_DOWNLOAD_SHELF_CONTEXT_MENU_CONTROLLER_H_
+
 #import <Cocoa/Cocoa.h>
 
 #import "ui/base/cocoa/menu_controller.h"
 #include "base/mac/scoped_nsobject.h"
 
 @class DownloadItemController;
 
 // MenuController that retains a DownloadItemController and instantiates a menu
 // based on the contextMenuModel from the DownloadItemController.
 @interface DownloadShelfContextMenuController : MenuController {
  @private
   base::scoped_nsobject<DownloadItemController> itemController_;
   id<NSMenuDelegate> menuDelegate_;
 }
 
 // Initializes the MenuController using [itemController contextMenuModel].
 // menuDelegate will be sent a menuDidClose message when the menu closes.
 - (id)initWithItemController:(DownloadItemController*)itemController
                 withDelegate:(id<NSMenuDelegate>)menuDelegate;
 
 - (void)menuDidClose:(NSMenu*)menu;
 @end
+
+#endif  // CHROME_BROWSER_UI_COCOA_DOWNLOAD_DOWNLOAD_SHELF_CONTEXT_MENU_CONTROLLER_H_