It might be easier simply to have all UMA metrics written to disk (not just user actions).  Or provide an easy way to make Android upload to a local UMA server from which we can extract and examine logs.

mpearson@, your usage of "easier" and "simply" are way different from mine :-)

I was thinking this could be done with two lines of code essentially:

if (<command line enabled>) {
  LOG(INFO) << "User action reported: " << user_action;
}

Writing to a local UMA server seems like it would require setting up a forwarder and building a local server somewhere that has easy printing logic.  Writing to disk would potentially work, but then we have to think about file size and deletion that are not free.

Another option would be finding a way to enable the webui tracking of user actions to be always running in with a command line instead of just when chrome://user-actions is opened.  But I don't know how intertwined that is with the webui flow and if that can be separated at all.

I like your simple two line version. :-)

The chrome://user-actions technique might be doable as well.  I don't think it's as good a solution as your easy proposal.  The biggest issues with the chrome://user-actions idea is:
* if Chrome gets killed, we have no way to view the recent actions.
* you'd have to revise the chrome://user-actions code to make it have memory.  Right now it has none.  (It observes and action, adds it to the page.  If you reload chrome://user-actions or open another chrome://user-actions you don't see the actions that a chrome://user-actions page has previously observed.)

(Yes, you're right, my "easier" solutions are not easy at all.  More general, yes.  Easy, no. :-) And probably unnecessary.)