Change ARC notification type from SIMPLE to BASE_FORMAT

Notification type SIMPLE is for the web notification actually and it triggers some hacks which causes the problem (see the issue).

This patch changes the type to BASE_FORMAT without hacks.

BUG=b/26831435

Review URL: https://codereview.chromium.org/1640333003

Cr-Commit-Position: refs/heads/master@{#372039}

ui/arc/notification/arc_notification_item.cc

@@ -110,11 +110,11 @@ void ArcNotificationItem::UpdateWithArcNotificationData(
 
   switch (data.type) {
     case ArcNotificationType::BASIC:
-      type = message_center::NOTIFICATION_TYPE_SIMPLE;
+      type = message_center::NOTIFICATION_TYPE_BASE_FORMAT;
       break;
     case ArcNotificationType::IMAGE:
       // TODO(yoshiki): Implement this types.
-      type = message_center::NOTIFICATION_TYPE_SIMPLE;
+      type = message_center::NOTIFICATION_TYPE_BASE_FORMAT;
       LOG(ERROR) << "Unsupported notification type: image";
       break;
     case ArcNotificationType::PROGRESS: