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

ui/message_center/cocoa/notification_controller.h

Index: ui/message_center/cocoa/notification_controller.h
diff --git a/ui/message_center/cocoa/notification_controller.h b/ui/message_center/cocoa/notification_controller.h
index 47f1e87b67d70aaa1937edfb4fd0179ecd7388b7..61a5e2f06665f5609cd35e1741ac9c2d663519bf 100644
--- a/ui/message_center/cocoa/notification_controller.h
+++ b/ui/message_center/cocoa/notification_controller.h
@@ -37,6 +37,9 @@ MESSAGE_CENTER_EXPORT
   // The button that invokes |-close:|, in the upper-right corner.
   base::scoped_nsobject<HoverImageButton> closeButton_;
 
+  // The small icon associated with the notification, on the bottom right.
+  base::scoped_nsobject<NSImageView> smallImage_;
+
   // The large icon associated with the notification, on the left side.
   base::scoped_nsobject<NSImageView> icon_;
 
@@ -84,6 +87,7 @@ MESSAGE_CENTER_EXPORT
 @end
 
 @interface MCNotificationController (TestingInterface)
+- (NSImageView*)smallImageView;
 - (NSImageView*)iconView;
 @end