Unity build does not start in Chrome if running on an iframe that has the gamepad security policy disabled.

Chrome has changed its behavior to start throwing a security exception if navigator.getGamepads() is called and the page is run from an insecure origin (without https:// URL)

If running Unity content on an iframe that does not have gamepad security policy enabled, Chrome might throw an exception (depending on origin trial)

This exception is reported to prevent Unity web content from running.

Gamepad support landed in November 2018 by 003606e82451fa068e441d6641368a4d8a24d964 .