Update first download notification correctly if there are multiple notifications

chrome/browser/download/notification/download_notification_manager.cc

 // 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/download/notification/download_notification_manager.h"
 
 #include "base/command_line.h"
 #include "base/strings/string_number_conversions.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/download/download_item_model.h"
@@ skipping 60 matching lines @@
 
 ///////////////////////////////////////////////////////////////////////////////
 // DownloadNotificationManagerForProfile implementation:
 ///////////////////////////////////////////////////////////////////////////////
 
 DownloadNotificationManagerForProfile::DownloadNotificationManagerForProfile(
     Profile* profile,
     DownloadNotificationManager* parent_manager)
     : profile_(profile),
       parent_manager_(parent_manager),
+      message_center_(g_browser_process->message_center()),
       items_deleter_(&items_) {
 }
 
 DownloadNotificationManagerForProfile::
     ~DownloadNotificationManagerForProfile() {
   for (const auto& download : items_) {
     download.first->RemoveObserver(this);
   }
 }
 
@@ skipping 55 matching lines @@
   for (auto& item : items_) {
     content::DownloadItem* download_item = item.first;
     DownloadItemNotification* download_notification = item.second;
     if (download_item->GetState() == content::DownloadItem::IN_PROGRESS)
       download_notification->DisablePopup();
   }
 
   DownloadItemNotification* item = new DownloadItemNotification(download, this);
   items_.insert(std::make_pair(download, item));
 }
+
+void DownloadNotificationManagerForProfile::OverrideMessageCenterForTest(
+    message_center::MessageCenter* message_center) {
+  DCHECK(message_center);
+  message_center_ = message_center;
+}