Add device path enumeration to the new Windows USB backend.

device/usb/usb_device_win.h

+// 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.
+
+#ifndef DEVICE_USB_USB_DEVICE_WIN_H_
+#define DEVICE_USB_USB_DEVICE_WIN_H_
+
+#include <string>
+
+#include "base/macros.h"
+#include "base/threading/thread_checker.h"
+#include "device/usb/usb_device.h"
+
+namespace base {
+class SequencedTaskRunner;
+}
+
+namespace device {
+
+class UsbDeviceWin : public UsbDevice {
+ public:
+  // UsbDevice implementation:
+  void Open(const OpenCallback& callback) override;
+
+ protected:
+  friend class UsbServiceWin;
+  friend class UsbDeviceHandleWin;
+
+  // Called by UsbServiceWin only;
+  UsbDeviceWin(const std::string& device_path,
+               const std::string& hub_path,
+               int port_number,
+               scoped_refptr<base::SequencedTaskRunner> task_runner);
+
+  ~UsbDeviceWin() override;
+
+  const std::string& device_path() const { return device_path_; }
+  int port_number() const { return port_number_; }
+
+ private:
+  base::ThreadChecker thread_checker_;
+
+  const std::string device_path_;
+  const std::string hub_path_;
+  const int port_number_;
+
+  scoped_refptr<base::SequencedTaskRunner> task_runner_;
+  scoped_refptr<base::SequencedTaskRunner> blocking_task_runner_;
+
+  DISALLOW_COPY_AND_ASSIGN(UsbDeviceWin);
+};
+
+}  // namespace device
+
+#endif  // DEVICE_USB_USB_DEVICE_WIN_H_