On the one hand, I don't think that's a very good definition of trolling. On the other hand that might be the best definition you could hope to plausibly classify things as in a regular research study, so maybe that's why they chose it. (Although of course even in general, "no reason" almost never exists; it's a question of who is doing the discerning, how far they can see, and how remote it is to whatever topic is at hand)
I'd describe classic trolling as something like: communication whose primary intent is covertly eliciting an asymmetric negative emotional situation for others with disregard for the personal authenticity of the communication. Most commonly this is also an asymmetric investment (a large response compared to the trolling) saying things the troll doesn't even particularly believe, and the negative emotional situation is frustration and exasperation that can sometimes border on anger, usually community-viewable. I don't think it requires true intent so I would also include "for no reason" -- any communication consistent with that intent unless it shows clear evidence of alternative rationales.
There are several things it's not, at least to me:
2) conventional bullying and/or personal attacks. This is almost by definition overt rather than covert. [Often it seems it does have a reason too, but that's murkier.
]
3) Any means to a discernible end. e.g. Trying to draw out someone's authentic responses to primarily show the community truth about them -- perhaps to publicly uncover lies or inconsistencies or unpopular positions to lower the social status of that person. I think it has to be about generating their emotional reaction for its own sake. Provoking a bully to show they are a bully is, instead, a means to an actual end.
4) It's common to have SIWOTIS (Someone Is Wrong On The Internet Syndrome) where you have a strong tendency (perhaps some compulsion) to try to correct people who are egregiously wrong about something and you perceive have some hope that you can convince them to come around to the "correct" position. This makes a lot of sense if this correction is "please don't drink gasoline" but isn't limited to that. This is the easiest way to become a troll VICTIM because it's the easiest thing to exploit: Just strongly assert something concrete that's very wrong.
5) There are a lot of versions of attempting to have topical discourse that can start to look a lot like it, but I would disqualify anything that is using earnestly held beliefs.
5a) Discussing random topics on the internet that perhaps have no practical value and seem like a waste of time... describes a lot of the Internet. They're not calling that trolling, but for context I'd argue the "no reason" part would still apply here.
5b) Doing the above, it's relatively easy to end up in an argument with a stranger on the internet, even quite accidentally, because you're saying things in front of many strangers without a lot of historical context about who each other are or a lot of present context about what's going on right now. I would not consider this trolling, just a common red herring.
5c) And of course even you didn't do it explicitly it's certainly even easier to end up in an escalating argument if you have unmanaged anger issues or are a bully etc. That's being an assh*le, but I would not consider it trolling.