Use udev for serial device enumeration on Linux

device/serial/serial_device_info.cc

Index: device/serial/serial_device_info.cc
diff --git a/device/serial/serial_device_info.cc b/device/serial/serial_device_info.cc
new file mode 100644
index 0000000000000000000000000000000000000000..865673f65c05bd5a9517d38ca8c8d4195aebec3a
--- /dev/null
+++ b/device/serial/serial_device_info.cc
@@ -0,0 +1,17 @@
+// Copyright (c) 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.
+
+#include "device/serial/serial_device_info.h"
+
+namespace device {
+
+SerialDeviceInfo::SerialDeviceInfo()
+    : vendor_id(0),
+      product_id(0) {
+}
+
+SerialDeviceInfo::~SerialDeviceInfo() {
+}
+
+}  // namespace devices