Display the first item for list mac native notifications

chrome/browser/notifications/notification_platform_bridge_mac.mm

 // 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.
 
 #include "chrome/browser/notifications/notification_platform_bridge_mac.h"
 
 #include <utility>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
@@ skipping 165 matching lines @@
   base::scoped_nsobject<NotificationBuilder> builder(
       [[NotificationBuilder alloc]
       initWithCloseLabel:l10n_util::GetNSString(IDS_NOTIFICATION_BUTTON_CLOSE)
             optionsLabel:l10n_util::GetNSString(IDS_NOTIFICATION_BUTTON_MORE)
            settingsLabel:l10n_util::GetNSString(
                              IDS_NOTIFICATION_BUTTON_SETTINGS)]);
 
   [builder
       setTitle:base::SysUTF16ToNSString(CreateNotificationTitle(notification))];
 
-  [builder setContextMessage:base::SysUTF16ToNSString(notification.message())];
+  base::string16 context_message =
+      notification.items().empty()
+          ? notification.message()
+          : (notification.items().at(0).title + base::UTF8ToUTF16(" - ") +
+             notification.items().at(0).message);
+
+  [builder setContextMessage:base::SysUTF16ToNSString(context_message)];
 
   bool requires_attribution =
       notification.context_message().empty() &&
       notification_type != NotificationCommon::EXTENSION;
 
   base::string16 subtitle =
       requires_attribution
           ? url_formatter::FormatOriginForSecurityDisplay(
                 url::Origin(notification.origin_url()),
                 url_formatter::SchemeDisplay::OMIT_HTTP_AND_HTTPS)
@@ skipping 352 matching lines @@
     base::scoped_nsobject<CrXPCMachPort> xpcPort(
         [[CrXPCMachPort alloc] initWithMachSendRight:std::move(exceptionPort)]);
     [proxy setMachExceptionPort:xpcPort];
     setExceptionPort_ = YES;
   }
 
   return proxy;
 }
 
 @end