Parse USB interface association descriptors.

device/usb/usb_descriptors.h

 // Copyright 2014 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.
 
 #ifndef DEVICE_USB_USB_DESCRIPTORS_H_
 #define DEVICE_USB_USB_DESCRIPTORS_H_
 
 #include <stdint.h>
 
 #include <map>
@@ skipping 67 matching lines @@
   UsbInterfaceDescriptor() = delete;
   ~UsbInterfaceDescriptor();
 
   uint8_t interface_number;
   uint8_t alternate_setting;
   uint8_t interface_class;
   uint8_t interface_subclass;
   uint8_t interface_protocol;
   std::vector<UsbEndpointDescriptor> endpoints;
   std::vector<uint8_t> extra_data;
+  // First interface of the function to which this interface belongs.
+  uint8_t first_interface;
 };
 
 struct UsbConfigDescriptor {
   UsbConfigDescriptor(uint8_t configuration_value,
                       bool self_powered,
                       bool remote_wakeup,
                       uint16_t maximum_power);
   UsbConfigDescriptor() = delete;
   ~UsbConfigDescriptor();
 
+  // Scans through |extra_data| for interface association descriptors and
+  // populates |first_interface| for each interface in this configuration.
+  void AssignFirstInterfaceNumbers();
+
   uint8_t configuration_value;
   bool self_powered;
   bool remote_wakeup;
   uint16_t maximum_power;
   std::vector<UsbInterfaceDescriptor> interfaces;
   std::vector<uint8_t> extra_data;
 };
 
 bool ParseUsbStringDescriptor(const std::vector<uint8_t>& descriptor,
                               base::string16* output);
 
 void ReadUsbStringDescriptors(
     scoped_refptr<UsbDeviceHandle> device_handle,
     scoped_ptr<std::map<uint8_t, base::string16>> index_map,
     const base::Callback<void(scoped_ptr<std::map<uint8_t, base::string16>>)>&
         callback);
 
 }  // namespace device
 
 #endif  // DEVICE_USB_USB_DESCRIPTORS_H_