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..1146d851a2dceea55f91be624f8ebd952fb4cbed
--- /dev/null
+++ b/device/serial/serial_device_info.cc
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+// 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