Update first download notification correctly if there are multiple notifications

chrome/browser/download/notification/download_notification_browsertest.cc

Index: chrome/browser/download/notification/download_notification_browsertest.cc
diff --git a/chrome/browser/download/notification/download_notification_browsertest.cc b/chrome/browser/download/notification/download_notification_browsertest.cc
index 4b72ddafcd3267bea4e296b8e9fd4a2e6d265bc3..8f28c4fbbec759503e5d8beb90a9fb1f71f4e7fe 100644
--- a/chrome/browser/download/notification/download_notification_browsertest.cc
+++ b/chrome/browser/download/notification/download_notification_browsertest.cc
@@ -374,6 +374,10 @@ IN_PROC_BROWSER_TEST_F(DownloadNotificationTest, DownloadFile) {
   EXPECT_EQ(message_center::NOTIFICATION_TYPE_PROGRESS,
             GetNotification(notification_id())->type());
 
+  // Confirms that the notification is updated periodically.
+  NotificationUpdateObserver download_notification_periodically_update_observer;

[asanka, 2015/10/12 18:59:08]

Does this rely on the DownloadItem firing UpdateObservers on its own? The fact
that an in-progress download sends OnDownloadUpdated() periodically even when no
data is transferred is undocumented behavior and is something we'd like to get
rid of.

If that's what you are relying on, a better alternative is to manually trigger
an update (via DownloadItem::UpdateObservers()) and then seeing if that results
in the download notification being updated. That also means that the below
Wait() call doesn't stall for however long it takes for the next timer initiated
update to fire.

[yoshiki, 2015/10/14 06:53:38]

Thank you for suggestion. Thanks. PTAL

+  download_notification_periodically_update_observer.Wait();
+
   NotificationUpdateObserver download_notification_update_observer;
 
   // Requests to complete the download.
@@ -784,6 +788,13 @@ IN_PROC_BROWSER_TEST_F(DownloadNotificationTest, MAYBE_DownloadMultipleFiles) {
   EXPECT_EQ(message_center::DEFAULT_PRIORITY,
             GetNotification(notification_id2)->priority());
 
+  // Confirms that both notifications are updated periodically.
+  std::set<std::string> updated_ids;
+  while (updated_ids.size() != 2) {
+    NotificationUpdateObserver notification_periodically_update_observer;
+    updated_ids.insert(notification_periodically_update_observer.Wait());
+  }
+
   // Requests to complete the downloads.
   ui_test_utils::NavigateToURL(
       browser(), GURL(net::URLRequestSlowDownloadJob::kFinishDownloadUrl));