Use interface associations to check function permissions.

device/usb/public/interfaces/device.mojom

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 module device.usb;
 
 enum OpenDeviceError {
   // Opening the device succeeded.
   OK,
 
@@ skipping 40 matching lines @@
   uint8 alternate_setting;
   uint8 class_code;
   uint8 subclass_code;
   uint8 protocol_code;
   string? interface_name;
   array<EndpointInfo> endpoints;
 };
 
 struct InterfaceInfo {
   uint8 interface_number;
+  // Interface number of the first interface in the function to which this
+  // interface belongs.
+  uint8 first_interface;
   array<AlternateInterfaceInfo> alternates;
 };
 
 struct ConfigurationInfo {
   uint8 configuration_value;
   string? configuration_name;
   array<InterfaceInfo> interfaces;
 };
 
 struct WebUsbFunctionSubset {
@@ skipping 205 matching lines @@
   // indicates no timeout: the request will remain pending indefinitely until
   // completed or otherwise terminated.
 
   // |packets| contains the status of each packet sent to the device, in order.
   IsochronousTransferOut(uint8 endpoint_number,
                          array<uint8> data,
                          array<uint32> packet_lengths,
                          uint32 timeout)
       => (array<IsochronousPacket> packets);
 };