Looks like it just goes to the first language in the list in alphabetical order. It should go to "Unknown" instead.

Unknown is not currently an option on that drop down box.

I guess there's a separate question: do we want to give users the option of insisting that the source language is unclear / unknown?

Not necessarily. In this case we can also show a blank. Mostly trying to figure out something less confusing the defaulting to first language in list.

Also I think this is an issue on ChromeOS and Windows as well.

Did you have a particular approach you wanted implemented? Should I add a blank option to the menu (which sends an unknown source language to the translate server)?

My preference would be to explicitly indicate that we couldn't resolve the page language. "Undetected"/"Unknown" both work for that purpose, but I can live with a blank. Adding Shimi in case she has an expert opinion.

+1 to explicitly indicate that the language is "Unknown"

Perfect. Let's go with "Unknown" then.

Issue 707209 has been merged into this issue.

Hey Michael, is this bug fixed with https://codereview.chromium.org/2867993002/?

Unfortunately not, that bug is mostly unrelated.

Status for this: it's much more complicated than I anticipated. Adding "Unknown" to the "source" drop down makes it visible for "target" too, and removing this effect will require coding/building/testing on >= 4 platforms.

Ok. Maybe keep this one in your back-pocket when you have some free time. Might be a good opportunity to work across the platforms.