I doubt it'll happen in the US because we don't really have workers dormitories for people to jump from and in the US very few people jump for suicides (~2%) vs guns (~56%), suffocation/hanging (~25%) or poisoning (~11%).
Ok, that makes more sense. So, I modify the question to be U.S. workers threatening mass suicide by gun or whatever with a good number at one plant over time. Then, the plant starts taking preventative measures against various suicide equipment instead of investing in working conditions.
You'd probably have to go back a ways to at least the early 1900s I'd guess to get the right combination of horribleness to get that. These days workplace suicides are relatively rare 1-2 per million workers. Also being poor sucks but US workers are waaay more mobile than a rural Chinese person who move into a company town from their home town/village so before they'd get to 'I'll kill myself in protest' they'll probably get to 'I'll change jobs or quit' first.
This actually has more odds of happening.