Add U2F device enumeration class

device/u2f/u2f_enumerate.h

Index: device/u2f/u2f_enumerate.h
diff --git a/device/u2f/u2f_enumerate.h b/device/u2f/u2f_enumerate.h
new file mode 100644
index 0000000000000000000000000000000000000000..5f7fe683894f31b2b44ecdd90e9a1dc52b84ebb2
--- /dev/null
+++ b/device/u2f/u2f_enumerate.h
@@ -0,0 +1,54 @@
+// 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_U2F_U2F_ENUMERATE_H_
+#define DEVICE_U2F_U2F_ENUMERATE_H_
+
+#include <list>
+
+#include "base/scoped_observer.h"
+#include "device/hid/hid_device_filter.h"
+#include "device/hid/hid_service.h"
+
+namespace device {
+class U2fDevice;
+
+class U2fEnumerate : HidService::Observer {
+ public:
+  using U2fEnumerateCallback =
+      base::OnceCallback<void(std::list<std::unique_ptr<U2fDevice>>)>;
+  using U2fDeviceAddedCallback =
+      base::RepeatingCallback<void(std::unique_ptr<U2fDevice>)>;
+  using U2fDeviceRemovedCallback =
+      base::RepeatingCallback<void(std::unique_ptr<U2fDevice>)>;
+
+  U2fEnumerate();
+  ~U2fEnumerate();
+
+  void EnumerateU2fDevices(U2fEnumerateCallback enumerate_cb);
+  void set_device_added_callback(
+      const U2fDeviceAddedCallback& device_added_cb) {
+    device_added_cb_ = device_added_cb;
+  }
+  void set_device_removed_callback(
+      const U2fDeviceRemovedCallback& device_removed_cb) {
+    device_removed_cb_ = device_removed_cb;
+  }
+
+ private:
+  void OnHidEnumerationComplete(
+      U2fEnumerate::U2fEnumerateCallback callback,
+      const std::vector<scoped_refptr<HidDeviceInfo>>& devices);
+  void OnDeviceAdded(scoped_refptr<HidDeviceInfo> device_info) override;
+  void OnDeviceRemoved(scoped_refptr<HidDeviceInfo> device_info) override;
+
+  HidDeviceFilter filter_;
+  U2fDeviceAddedCallback device_added_cb_;
+  U2fDeviceRemovedCallback device_removed_cb_;
+  ScopedObserver<HidService, HidService::Observer> hid_service_observer_;
+  base::WeakPtrFactory<U2fEnumerate> weak_factory_;
+};
+
+}  // namespace device
+#endif  // DEVICE_U2F_U2F_ENUMERATE_H_