Add support for reading USB descriptors to the new Windows backend.

device/usb/usb_service_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_service_win.h"
 
 #include <setupapi.h>
 #include <stdint.h>
 #include <usbiodef.h>
 
@@ skipping 316 matching lines @@
 
 void UsbServiceWin::CreateDeviceObject(const std::string& device_path,
                                        const std::string& hub_path,
                                        int port_number) {
   // Devices that appear during initial enumeration are gathered into the first
   // result returned by GetDevices() and prevent device add/remove notifications
   // from being sent.
   if (!enumeration_ready())
     ++first_enumeration_countdown_;
 
-  scoped_refptr<UsbDeviceWin> device(new UsbDeviceWin(
-      device_path, hub_path, port_number, blocking_task_runner()));
+  scoped_refptr<UsbDeviceWin> device(
+      new UsbDeviceWin(device_path, hub_path, port_number, task_runner()));
   devices_by_path_[device->device_path()] = device;
-
-  // TODO(reillyg): Read device descriptors.
-  DeviceReady(device, true);
+  device->ReadDescriptors(base::Bind(&UsbServiceWin::DeviceReady,
+                                     weak_factory_.GetWeakPtr(), device));
 }
 
 void UsbServiceWin::DeviceReady(scoped_refptr<UsbDeviceWin> device,
                                 bool success) {
   DCHECK(CalledOnValidThread());
 
   bool enumeration_became_ready = false;
   if (!enumeration_ready()) {
     DCHECK_GT(first_enumeration_countdown_, 0u);
     first_enumeration_countdown_--;
@@ skipping 27 matching lines @@
       result.push_back(map_entry.second);
     for (const auto& callback : enumeration_callbacks_)
       callback.Run(result);
     enumeration_callbacks_.clear();
   } else if (success && enumeration_ready()) {
     NotifyDeviceAdded(device);
   }
 }
 
 }  // namespace device