Help identifying " "MessageExtension-Madrid" in ios logs
Wow, that was an interesting little Google detour... 

According to this page, 'Madrid' was the codename for the iMessages app when it was still in development, and apparently elements of the internal structure — database names, components, etc — were developed using the code name and have not been changed since. 

Now, even if you don't use the Messages app ('Madrid' became 'iMessages' became 'Messages'), Messages is so thoroughly integrated into the OS that some of its components are bound to be invoked. From what you posted it looks like some background daemon is loading a notification extension into the system. That's a bit of code that lurks in the background and posts notifications on the screen if you get text messages. That extension, in turn, is checking in with the Messages app, which is why 'Madrid' is popping up in your logs. This entry seems completely normal to me, so I wouldn't worry.