Add U2F request state machines

device/u2f/u2f_request.h

Index: device/u2f/u2f_request.h
diff --git a/device/u2f/u2f_request.h b/device/u2f/u2f_request.h
new file mode 100644
index 0000000000000000000000000000000000000000..902a2ca84d6f51275e2a93b97c9c37a6722dff72
--- /dev/null
+++ b/device/u2f/u2f_request.h
@@ -0,0 +1,65 @@
+// 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_REQUEST_H_
+#define DEVICE_U2F_U2F_REQUEST_H_
+
+#include "base/cancelable_callback.h"
+#include "base/scoped_observer.h"
+#include "device/hid/hid_device_filter.h"
+#include "device/hid/hid_service.h"
+#include "u2f_device.h"
+
+namespace device {
+class U2fRequest : HidService::Observer {
+ public:
+  using ResponseCallback = base::Callback<void(U2fReturnCode status_code,
+                                               std::vector<uint8_t> response)>;
+
+  U2fRequest(const ResponseCallback& callback);
+  virtual ~U2fRequest();
+
+  void Start();
+  void AddDeviceForTesting(std::unique_ptr<U2fDevice> device);
+
+ protected:
+  enum class State {
+    INIT,
+    BUSY,
+    WINK,
+    IDLE,
+    OFF,
+    COMPLETE,
+  };
+
+  void Transition();
+  virtual void TryDevice() = 0;
+
+  std::unique_ptr<U2fDevice> current_device_;
+  State state_;
+  ResponseCallback cb_;
+
+ private:
+  FRIEND_TEST_ALL_PREFIXES(U2fRequestTest, TestAddRemoveDevice);
+  FRIEND_TEST_ALL_PREFIXES(U2fRequestTest, TestIterateDevice);
+  FRIEND_TEST_ALL_PREFIXES(U2fRequestTest, TestBasicMachine);
+
+  void Enumerate();
+  void IterateDevice();
+  void OnWaitComplete();
+  void AddDevice(std::unique_ptr<U2fDevice> device);
+  void OnDeviceAdded(scoped_refptr<HidDeviceInfo> device_info) override;
+  void OnDeviceRemoved(scoped_refptr<HidDeviceInfo> device_info) override;
+  void OnEnumerate(const std::vector<scoped_refptr<HidDeviceInfo>>& devices);
+
+  std::list<std::unique_ptr<U2fDevice>> devices_;
+  std::list<std::unique_ptr<U2fDevice>> attempted_devices_;
+  base::CancelableClosure delay_callback_;
+  HidDeviceFilter filter_;
+  ScopedObserver<HidService, HidService::Observer> hid_service_observer_;
+  base::WeakPtrFactory<U2fRequest> weak_factory_;
+};
+}  // namespace device
+
+#endif  // DEVICE_U2F_U2F_REQUEST_H_