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

ui/message_center/message_center_impl.cc

Index: ui/message_center/message_center_impl.cc
diff --git a/ui/message_center/message_center_impl.cc b/ui/message_center/message_center_impl.cc
index fe38696e2ff9696cbd6badc57a228a0ffa20d916..b9dfb23e73c5a2d303d5b69a2dc258f30b65a603 100644
--- a/ui/message_center/message_center_impl.cc
+++ b/ui/message_center/message_center_impl.cc
@@ -750,6 +750,28 @@ void MessageCenterImpl::SetNotificationButtonIcon(
   }
 }
 
+void MessageCenterImpl::SetNotificationSmallImage(
+    const std::string& notification_id,
+    const gfx::Image& image) {
+  bool updated = false;
+  Notification* queue_notification =
+      notification_queue_->GetLatestNotification(notification_id);
+
+  if (queue_notification) {
+    queue_notification->set_small_image(image);
+    updated = true;
+  } else {
+    updated =
+        notification_list_->SetNotificationSmallImage(notification_id, image);
+  }
+
+  if (updated) {
+    FOR_EACH_OBSERVER(MessageCenterObserver,
+                      observer_list_,
+                      OnNotificationUpdated(notification_id));
+  }
+}
+
 void MessageCenterImpl::DisableNotificationsByNotifier(
     const NotifierId& notifier_id) {
   if (settings_provider_) {