Update device/usb and its Mojo interface for variable size ISO packets.

device/devices_app/usb/type_converters.h

Index: device/devices_app/usb/type_converters.h
diff --git a/device/devices_app/usb/type_converters.h b/device/devices_app/usb/type_converters.h
index c220178103e833e2c722a9ff426fd7fe8e556c33..654db11a7215b0ca179855967e252b9ae1b96d6b 100644
--- a/device/devices_app/usb/type_converters.h
+++ b/device/devices_app/usb/type_converters.h
@@ -121,6 +121,13 @@ struct TypeConverter<device::usb::DeviceInfoPtr, device::UsbDevice> {
   static device::usb::DeviceInfoPtr Convert(const device::UsbDevice& device);
 };
 
+template <>
+struct TypeConverter<device::usb::IsochronousPacketPtr,
+                     device::UsbDeviceHandle::IsochronousPacket> {
+  static device::usb::IsochronousPacketPtr Convert(
+      const device::UsbDeviceHandle::IsochronousPacket& packet);
+};
+
 }  // namespace mojo
 
 #endif  // DEVICE_DEVICES_APP_USB_TYPE_CONVERTERS_H_