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

ui/message_center/message_center_impl.h

Index: ui/message_center/message_center_impl.h
diff --git a/ui/message_center/message_center_impl.h b/ui/message_center/message_center_impl.h
index faee65818042d4ab0a4c94e5691740ac1cb385c6..d0b6f03674ea391bd922cfaf6009c4682b262af6 100644
--- a/ui/message_center/message_center_impl.h
+++ b/ui/message_center/message_center_impl.h
@@ -170,6 +170,8 @@ class MessageCenterImpl : public MessageCenter,
   virtual void SetNotificationButtonIcon(const std::string& notification_id,
                                          int button_index,
                                          const gfx::Image& image) OVERRIDE;
+  virtual void SetNotificationSmallImage(const std::string& notification_id,
+                                         const gfx::Image& image) OVERRIDE;
   virtual void DisableNotificationsByNotifier(
       const NotifierId& notifier_id) OVERRIDE;
   virtual void ExpandNotification(const std::string& id) OVERRIDE;