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 59c2f4c6b3394a88f022f3d0abec6a52cf179e0b..15484ea6b6dca0224e9899c70b9fef2d3348ca33 100644
--- a/device/devices_app/usb/type_converters.h
+++ b/device/devices_app/usb/type_converters.h
@@ -16,8 +16,9 @@
 #include "mojo/public/cpp/bindings/array.h"
 #include "mojo/public/cpp/bindings/type_converter.h"
 
-// Type converters to convert objects between internal device/usb data types and
-// public Mojo interface data types.
+// Type converters to translate between internal device/usb data types and
+// public Mojo interface data types. This must be included by any source file
+// that uses these conversions explicitly or implicitly.
 
 namespace device {
 class UsbDevice;
@@ -121,6 +122,13 @@ 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_