Add device path enumeration to the new Windows USB backend.

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"
 
 #include "base/guid.h"
 #include "device/usb/usb_device_handle.h"
 #include "device/usb/webusb_descriptors.h"
 
 namespace device {
 
 UsbDevice::Observer::~Observer() {}
 
 void UsbDevice::Observer::OnDeviceRemoved(scoped_refptr<UsbDevice> device) {}
 
+UsbDevice::UsbDevice() : guid_(base::GenerateGUID()) {}
+
 UsbDevice::UsbDevice(const UsbDeviceDescriptor& descriptor,
                      const base::string16& manufacturer_string,
                      const base::string16& product_string,
                      const base::string16& serial_number)
     : descriptor_(descriptor),
       manufacturer_string_(manufacturer_string),
       product_string_(product_string),
       serial_number_(serial_number),
       guid_(base::GenerateGUID()) {}
 
@@ skipping 13 matching lines @@
       guid_(base::GenerateGUID()) {
   descriptor_.usb_version = usb_version;
   descriptor_.device_class = device_class;
   descriptor_.device_subclass = device_subclass;
   descriptor_.device_protocol = device_protocol;
   descriptor_.vendor_id = vendor_id;
   descriptor_.product_id = product_id;
   descriptor_.device_version = device_version;
 }
 
-UsbDevice::~UsbDevice() {
-}
+UsbDevice::~UsbDevice() {}
 
 void UsbDevice::CheckUsbAccess(const ResultCallback& callback) {
   // By default assume that access to the device is allowed. This is implemented
   // on Chrome OS by checking with permission_broker.
   callback.Run(true);
 }
 
 void UsbDevice::RequestPermission(const ResultCallback& callback) {
   // By default assume that access to the device is allowed. This is implemented
   // on Android by calling android.hardware.usb.UsbManger.requestPermission.
@@ skipping 32 matching lines @@
   handles.swap(handles_);
   for (auto* handle : handles_)
     handle->Close();
 }
 
 void UsbDevice::HandleClosed(UsbDeviceHandle* handle) {
   handles_.remove(handle);
 }
 
 }  // namespace device