[Easy Unlock] Port the BluetoothThrottler class to native code.

components/proximity_auth/bluetooth_throttler_impl.h

+// 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.
+
+#ifndef COMPONENTS_PROXIMITY_AUTH_BLUETOOTH_THROTTLER_IMPL_H
+#define COMPONENTS_PROXIMITY_AUTH_BLUETOOTH_THROTTLER_IMPL_H
+
+#include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/time/time.h"
+#include "components/proximity_auth/bluetooth_throttler.h"
+
+namespace base {
+class TickClock;
+}
+
+namespace proximity_auth {
+
+// This class throttles repeated connection attempts to the same device. This
+// throttling is necessary to prevent a kernel race condition when connecting
+// before the previous connection fully closes, putting the connection in a
+// corrupted, and unrecoverable state. http://crbug.com/345232
+class BluetoothThrottlerImpl : public BluetoothThrottler {
+ public:
+  // Creates a throttler for connections to a remote device, using the |clock|
+  // as a time source.
+  explicit BluetoothThrottlerImpl(scoped_ptr<base::TickClock> clock);
+  ~BluetoothThrottlerImpl() override;
+
+  // BluetoothThrottler:
+  base::TimeDelta GetDelay() const override;
+  void OnConnectionClosed() override;
+
+ protected:
+  // Returns the duration to wait, after disconnecting, before reattempting a
+  // connection to the remote device. Exposed for testing.
+  base::TimeDelta GetCooldownTimeDelta() const;
+
+ private:
+  // Tracks the last seen disconnect time for the |remote_device_|.
+  base::TimeTicks last_disconnect_time_;
+
+  // The time source.
+  scoped_ptr<base::TickClock> clock_;
+
+  DISALLOW_COPY_AND_ASSIGN(BluetoothThrottlerImpl);
+};
+
+}  // namespace proximity_auth
+
+#endif  // COMPONENTS_PROXIMITY_AUTH_BLUETOOTH_THROTTLER_IMPL_H