Add U2F device enumeration class

device/u2f/u2f_hid_device.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 "u2f_hid_device.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/command_line.h"
 #include "crypto/random.h"
@@ skipping 280 matching lines @@
       base::Bind(&U2fHidDevice::OnWink, weak_factory_.GetWeakPtr(), callback));
 }
 
 void U2fHidDevice::OnWink(const WinkCallback& callback,
                           bool success,
                           std::unique_ptr<U2fMessage> response) {
   callback.Run();
 }
 
 std::string U2fHidDevice::GetId() {
-  std::ostringstream id("hid:");
+  std::ostringstream id("hid:", std::ios::ate);
   id << device_info_->device_id();
   return id.str();
 }
 
 // static
 bool U2fHidDevice::IsTestEnabled() {
   base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
   return command_line->HasSwitch(switches::kEnableU2fHidTest);
 }
 
 }  // namespace device