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

components/proximity_auth/bluetooth_throttler_impl.h

Index: components/proximity_auth/bluetooth_throttler_impl.h
diff --git a/components/proximity_auth/bluetooth_throttler_impl.h b/components/proximity_auth/bluetooth_throttler_impl.h
new file mode 100644
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+++ b/components/proximity_auth/bluetooth_throttler_impl.h
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+// 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 <set>
+
+#include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/time/time.h"
+#include "components/proximity_auth/bluetooth_throttler.h"
+#include "components/proximity_auth/connection_observer.h"
+
+namespace base {
+class TickClock;
+}
+
+namespace proximity_auth {
+
+class Connection;
+
+// 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 ConnectionObserver {
+ 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 OnConnection(Connection* connection) 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:
+  // ConnectionObserver:
+  void OnConnectionStatusChanged(Connection* connection,
+                                 Connection::Status old_status,
+                                 Connection::Status new_status) override;
+
+  // Tracks the last seen disconnect time for the |remote_device_|.
+  base::TimeTicks last_disconnect_time_;
+
+  // The time source.
+  scoped_ptr<base::TickClock> clock_;
+
+  // The currently connected connections.
+  // Each connection is stored as a weak reference, which is safe because |this|
+  // instance is registered as an observer, and will unregister when the
+  // connection disconnects, which is guaranteed to occur before the connection
+  // is destroyed.
+  std::set<Connection*> connections_;
+
+  DISALLOW_COPY_AND_ASSIGN(BluetoothThrottlerImpl);
+};
+
+}  // namespace proximity_auth
+
+#endif  // COMPONENTS_PROXIMITY_AUTH_BLUETOOTH_THROTTLER_IMPL_H