I've got an Android application which can be remote controlled by USB midi devices. The app itself is running fine with google ARC but the USB module doesn't detect any USB device. I already found that it is possible for Chrome apps to use usb but only when declaring each specific device in the manifest (https://developer.chrome.com/apps/app_usb).
Does Google ARC support USB access? Will it be possible to get a list with all USB devices without declaring them first in the manifest?
Sorry, ARC does not currently implement a USB service that proxies to the Chrome USB interface.
Feel free to file a bug however.
If we do implement it, is will likely have the same limit where you must predeclare the devices you want access to, for the same reason listed on the page you link to.