Convert WindowOpenDisposition to an enum class.

chrome/browser/ui/cocoa/history_menu_cocoa_controller.mm

 // Copyright (c) 2012 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.
 
 #import "chrome/browser/ui/cocoa/history_menu_cocoa_controller.h"
 
 #import "base/mac/foundation_util.h"
 #include "chrome/app/chrome_command_ids.h"  // IDC_HISTORY_MENU
 #import "chrome/browser/app_controller_mac.h"
 #include "chrome/browser/profiles/profile.h"
@@ skipping 31 matching lines @@
 // Open the URL of the given history item in the current tab.
 - (void)openURLForItem:(const HistoryMenuBridge::HistoryItem*)node {
   // If this item can be restored using TabRestoreService, do so. Otherwise,
   // just load the URL.
   sessions::TabRestoreService* service =
       TabRestoreServiceFactory::GetForProfile(bridge_->profile());
   if (node->session_id && service) {
     Browser* browser = chrome::FindTabbedBrowser(bridge_->profile(), false);
     BrowserLiveTabContext* context =
         browser ? browser->live_tab_context() : NULL;
-    service->RestoreEntryById(context, node->session_id, UNKNOWN);
+    service->RestoreEntryById(context, node->session_id,
+                              WindowOpenDisposition::UNKNOWN);
   } else {
     DCHECK(node->url.is_valid());
     WindowOpenDisposition disposition =
         ui::WindowOpenDispositionFromNSEvent([NSApp currentEvent]);
     chrome::NavigateParams params(bridge_->profile(), node->url,
         ui::PAGE_TRANSITION_AUTO_BOOKMARK);
     params.disposition = disposition;
     chrome::Navigate(&params);
   }
 }
 
 - (IBAction)openHistoryMenuItem:(id)sender {
   const HistoryMenuBridge::HistoryItem* item =
       bridge_->HistoryItemForMenuItem(sender);
   [self openURLForItem:item];
 }
 
 @end  // HistoryMenuCocoaController