[CrOS Tether] Create KeepAliveScheduler, a class which schedules keep-alive tickles to be sent to a…

chromeos/components/tether/keep_alive_scheduler.h

+// 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 CHROMEOS_COMPONENTS_TETHER_KEEP_ALIVE_SCHEDULER_H_
+#define CHROMEOS_COMPONENTS_TETHER_KEEP_ALIVE_SCHEDULER_H_
+
+#include <memory>
+
+#include "base/macros.h"
+#include "base/memory/weak_ptr.h"
+#include "base/timer/timer.h"
+#include "chromeos/components/tether/active_host.h"
+#include "chromeos/components/tether/keep_alive_operation.h"
+
+namespace chromeos {
+
+namespace tether {
+
+// Schedules keep-alive messages to be sent when this device is connected to a
+// remote device's tether hotspot. When a device connects, a keep-alive message
+// is sent immediately, then another one is scheduled every 4 minutes until the
+// device disconnects.
+class KeepAliveScheduler : public ActiveHost::Observer,
+                           public KeepAliveOperation::Observer {
+ public:
+  KeepAliveScheduler(ActiveHost* active_host,
+                     BleConnectionManager* connection_manager);
+  virtual ~KeepAliveScheduler();
+
+  // ActiveHost::Observer:
+  void OnActiveHostChanged(ActiveHost::ActiveHostStatus active_host_status,
+                           std::unique_ptr<cryptauth::RemoteDevice> active_host,
+                           const std::string& wifi_network_id) override;
+
+  // KeepAliveOperation::Observer:
+  void OnOperationFinished() override;
+
+ private:
+  friend class KeepAliveSchedulerTest;
+
+  KeepAliveScheduler(ActiveHost* active_host,
+                     BleConnectionManager* connection_manager,
+                     std::unique_ptr<base::Timer> timer);
+
+  void SendKeepAliveTickle();
+
+  static const uint32_t kKeepAliveIntervalMinutes;
+
+  ActiveHost* active_host_;
+  BleConnectionManager* connection_manager_;
+
+  std::unique_ptr<base::Timer> timer_;
+  std::unique_ptr<cryptauth::RemoteDevice> active_host_device_;
+  std::unique_ptr<KeepAliveOperation> keep_alive_operation_;
+
+  base::WeakPtrFactory<KeepAliveScheduler> weak_ptr_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(KeepAliveScheduler);
+};
+
+}  // namespace tether
+
+}  // namespace chromeos
+
+#endif  // CHROMEOS_COMPONENTS_TETHER_KEEP_ALIVE_SCHEDULER_H_