This blocklist allows access to particular models of USB device via the
WebUSB API to be blocked via either a binary push or Finch experiment.

Manual testing of this is difficult. I added a real device to the
blocklist and verified that it was not returned by
navigator.usb.getDevices() and was not listed in the chooser.

BUG=674353

Review-Url: https://codereview.chromium.org/2581543002
Cr-Commit-Position: refs/heads/master@{#438981}