Adds a small icon to notifications, and connects it to synced notifications.

ui/message_center/notification_list.cc

Index: ui/message_center/notification_list.cc
diff --git a/ui/message_center/notification_list.cc b/ui/message_center/notification_list.cc
index 3ec0bfe29643b1f67e5fa9666c538dd90e09f7a1..5da3f7a8fb659362410ac3081cbd5c223b6764e6 100644
--- a/ui/message_center/notification_list.cc
+++ b/ui/message_center/notification_list.cc
@@ -158,6 +158,16 @@ bool NotificationList::SetNotificationButtonIcon(
   return true;
 }
 
+bool NotificationList::SetNotificationSmallImage(
+    const std::string& notification_id,
+    const gfx::Image& image) {
+  Notifications::iterator iter = GetNotification(notification_id);
+  if (iter == notifications_.end())
+    return false;
+  (*iter)->set_small_image(image);
+  return true;
+}
+
 bool NotificationList::HasNotification(const std::string& id) {
   return GetNotification(id) != notifications_.end();
 }