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()
+    : usb_version_(0),

[scheib, 2017/02/14 19:40:05]

It's fine, but did you consider using default member initializers in the
declaration? Seems more robust to future edits (hard to forget to add in member
list and constructors)

[Reilly Grant (use Gerrit), 2017/02/15 22:03:13]

Fixed. I was just waiting for another patch to land that removed all but the
guid_ field from this list.

+      device_version_(0),
+      guid_(base::GenerateGUID()),
+      device_class_(0),
+      device_subclass_(0),
+      device_protocol_(0),
+      vendor_id_(0),
+      product_id_(0) {}
+
 UsbDevice::UsbDevice(uint16_t usb_version,
                      uint8_t device_class,
                      uint8_t device_subclass,
                      uint8_t device_protocol,
                      uint16_t vendor_id,
                      uint16_t product_id,
                      uint16_t device_version,
                      const base::string16& manufacturer_string,
                      const base::string16& product_string,
                      const base::string16& serial_number)
     : usb_version_(usb_version),
       device_version_(device_version),
       manufacturer_string_(manufacturer_string),
       product_string_(product_string),
       serial_number_(serial_number),
       guid_(base::GenerateGUID()),
       device_class_(device_class),
       device_subclass_(device_subclass),
       device_protocol_(device_protocol),
       vendor_id_(vendor_id),
       product_id_(product_id) {}
 
-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