Move device/usb classes from the FILE thread to UI thread.

device/usb/usb_device.cc

+// Copyright 2015 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/usb/usb_device.h"
+
+namespace device {
+
+UsbDevice::UsbDevice(uint16 vendor_id,
+                     uint16 product_id,
+                     uint32 unique_id,
+                     const base::string16& manufacturer_string,
+                     const base::string16& product_string,
+                     const base::string16& serial_number)
+    : vendor_id_(vendor_id),
+      product_id_(product_id),
+      unique_id_(unique_id),
+      manufacturer_string_(manufacturer_string),
+      product_string_(product_string),
+      serial_number_(serial_number) {
+}
+
+UsbDevice::~UsbDevice() {
+}
+
+}  // namespace device