Add device path enumeration to the new Windows USB backend.

device/usb/usb_device_win.cc

+// Copyright 2017 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_win.h"
+
+#include "base/bind.h"
+#include "base/memory/ptr_util.h"
+#include "base/sequenced_task_runner.h"
+#include "base/single_thread_task_runner.h"
+#include "base/threading/thread_task_runner_handle.h"
+#include "components/device_event_log/device_event_log.h"
+#include "device/usb/usb_device_handle.h"
+
+namespace device {
+
+UsbDeviceWin::UsbDeviceWin(
+    const std::string& device_path,
+    const std::string& hub_path,
+    int port_number,
+    scoped_refptr<base::SequencedTaskRunner> blocking_task_runner)
+    : device_path_(device_path),
+      hub_path_(hub_path),
+      port_number_(port_number),
+      task_runner_(base::ThreadTaskRunnerHandle::Get()),
+      blocking_task_runner_(std::move(blocking_task_runner)) {}
+
+UsbDeviceWin::~UsbDeviceWin() {}
+
+void UsbDeviceWin::Open(const OpenCallback& callback) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  task_runner_->PostTask(FROM_HERE, base::Bind(callback, nullptr));
+}
+
+}  // namespace device