This is working as intended. The commit message is directed at users of the chrome.usb API, who have the opportunity to move to chrome.hid.

For WebUSB, blocking of HID and other sensitive interface classes was announced here and will be rolling out in Chrome 67:

https://groups.google.com/a/chromium.org/d/msg/blink-dev/LZXocaeCwDw/GLfAffGLAAAJ

HID interfaces are blocked because developers should be using key/mouse events or the Gamepad API to read data from human interface devices. If you have a device which implements a vendor-specific protocol (i.e. not a standard HID device) then it should advertise a vendor-specific USB interface which will work with WebUSB.

On 65.0.3325.181 I'm receiving the same error on a USB to UART device with a 0xff vendor specific class. I'm able to enumerate, but not open. THIS IS EXPECTED as the device is bound to the driver "silabs".

However, when I change the PID to another value(Using a firmware utility) so the driver does not capture the device then the device does not show in chrome://device-log or the picker for libusb (navigator.usb.getDevices()).

Here is the device info. I tried 10c4:1234 and 10c4:eaff. The original is 10c4:ea60:

Bus 003 Device 004: ID 10c4:eaff Cygnal Integrated Products, Inc. 
Device Descriptor:
  bLength                18
  bDescriptorType         1
  bcdUSB               1.10
  bDeviceClass            0 (Defined at Interface level)
  bDeviceSubClass         0 
  bDeviceProtocol         0 
  bMaxPacketSize0        64
  idVendor           0x10c4 Cygnal Integrated Products, Inc.
  idProduct          0xeaff 
  bcdDevice            1.00
  iManufacturer           1 Silicon Labs
  iProduct                2 IPAY CP2102 USB to UART Bridge Controller
  iSerial                 3 1234
  bNumConfigurations      1
  Configuration Descriptor:
    bLength                 9
    bDescriptorType         2
    wTotalLength           32
    bNumInterfaces          1
    bConfigurationValue     1
    iConfiguration          0 
    bmAttributes         0x80
      (Bus Powered)
    MaxPower              100mA
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        0
      bAlternateSetting       0
      bNumEndpoints           2
      bInterfaceClass       255 Vendor Specific Class
      bInterfaceSubClass      0 
      bInterfaceProtocol      0 
      iInterface              2 IPAY CP2102 USB to UART Bridge Controller
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x81  EP 1 IN
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0040  1x 64 bytes
        bInterval               0
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x01  EP 1 OUT
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0040  1x 64 bytes
        bInterval               0
Device Status:     0x0000
  (Bus Powered)

I'm unsure whether I should open a new bug report for this or not.

Thanks,

Allan

This is because, on Windows, the OS needs to know to load the winusb.sys driver or else a user-space application like Chrome has no way to talk to the device. There are two ways to do this:

1. Manually install an INF file like this one to tell Windows to load the right driver (update the device IDs to match yours):

https://chromium.googlesource.com/chromium/src/+/master/tools/usb_gadget/usb_gadget.inf

2. Modify the device firmware to include Microsoft OS 2.0 Descriptors that include "WINUSB" as a Compatible ID:

https://docs.microsoft.com/en-us/windows-hardware/drivers/usbcon/microsoft-defined-usb-descriptors

Example firmware code for doing this is part of this Arduino library:

https://github.com/webusb/arduino/blob/gh-pages/library/WebUSB/WebUSB.cpp

This approach will work for Windows 8.1 and above.

Thank you!