CrOS Tether: Create HostScanScheduler, which schedules scans for devices which can serve as tether …

chromeos/components/tether/host_scan_scheduler.h

Index: chromeos/components/tether/host_scan_scheduler.h
diff --git a/chromeos/components/tether/host_scan_scheduler.h b/chromeos/components/tether/host_scan_scheduler.h
new file mode 100644
index 0000000000000000000000000000000000000000..c68d8b7fe6981bf70f317a3d1e0b93b2cec8c706
--- /dev/null
+++ b/chromeos/components/tether/host_scan_scheduler.h
@@ -0,0 +1,112 @@
+// Copyright 2016 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_HOST_SCAN_SCHEDULER_H
+#define CHROMEOS_COMPONENTS_TETHER_HOST_SCAN_SCHEDULER_H
+
+#include "chromeos/dbus/power_manager_client.h"
+#include "chromeos/login/login_state.h"
+#include "chromeos/network/network_state_handler_observer.h"
+#include "components/cryptauth/cryptauth_device_manager.h"
+
+namespace content {
+class BrowserContext;
+}
+
+namespace cryptauth {
+class CryptAuthDeviceManager;
+}
+
+namespace chromeos {
+
+class LoginState;
+class PowerManagerClient;
+
+namespace tether {
+
+class HostScanner;
+
+// Schedules scans for tether hosts. To start a scan attempt, three conditions
+// must be true:
+//
+//   (1) The user has just started using the device; specifically, the user has

[Tim Song, 2016/12/17 05:13:41]

"started using the device" is a bit confusing, due to multi-profile use cases. I
would just delete this sentence.

[Kyle Horimoto, 2016/12/19 21:10:47]

Done.

+//       just logged in or has just resumed using the device after it had been
+//       sleeping/suspended.
+//   (2) The device does not have an Internet connection.
+//   (3) The device has synced data about other devices belonging to the user's
+//       account, and at least one of those devices is capable of being a tether
+//       host (i.e., it has a mobile data connection).
+//
+// When one of those conditions changes, this class checks the conditions and
+// starts a scan automatically. Alternatively, a scan can be explicitly
+// triggered via ScheduleScanNowIfPossible().
+class HostScanScheduler : public LoginState::Observer,
+                          public PowerManagerClient::Observer,
+                          public NetworkStateHandlerObserver,
+                          public cryptauth::CryptAuthDeviceManager::Observer {
+ public:
+  HostScanScheduler(const content::BrowserContext* browser_context,
+                    std::unique_ptr<HostScanner> host_scanner);
+  ~HostScanScheduler() override;
+
+  // Sets up listeners so that scans can be automatically triggered when
+  // needed.
+  void InitializeAutomaticScans();
+
+  // Schedules a scan now if the three conditions described above are met and
+  // returns whether the scan was started.
+  bool ScheduleScanNowIfPossible();
+
+  // LoginState::Observer
+  void LoggedInStateChanged() override;
+
+  // PowerManagerClient::Observer
+  void SuspendDone(const base::TimeDelta& sleep_duration) override;
+
+  // NetworkStateHandlerObserver
+  void NetworkConnectionStateChanged(const NetworkState* network) override;
+
+  // cryptauth::CryptAuthDeviceManager::Observer
+  void OnSyncFinished(cryptauth::CryptAuthDeviceManager::SyncResult sync_result,
+                      cryptauth::CryptAuthDeviceManager::DeviceChangeResult
+                          device_change_result) override;

[Tim Song, 2016/12/17 05:13:41]

indenting issue

[Kyle Horimoto, 2016/12/19 21:10:47]

This was intentional since it doesn't fit on the previous line.

+
+ private:
+  friend class HostScanSchedulerTest;
+
+  class Context {

[Tim Song, 2016/12/17 05:13:41]

A more conventional name for this would be Delegate.

[Kyle Horimoto, 2016/12/19 21:10:47]

Done.

+   public:
+    virtual void AddObserver(HostScanScheduler* host_scan_scheduler) = 0;

[Tim Song, 2016/12/17 05:13:41]

Maybe a better name would be observeSystemEvents(). AddObserver() is a bit
confusing.

[Kyle Horimoto, 2016/12/19 21:10:47]

I'd like to keep Add/Remove since we really are just observing events from the
delegate.

+    virtual void RemoveObserver(HostScanScheduler* host_scan_scheduler) = 0;
+    virtual bool IsAuthenticatedUserLoggedIn() const = 0;
+    virtual bool IsNetworkConnectedOrConnecting() const = 0;
+    virtual bool AreTetherHostsSynced() const = 0;
+  };
+
+  class ContextImpl : public Context {

[Tim Song, 2016/12/17 05:13:41]

You can move this to the .cc file.

[Kyle Horimoto, 2016/12/19 21:10:47]

This isn't possible since it extends Context, which is a private class.

+   public:
+    ContextImpl(const content::BrowserContext* browser_context);
+
+    void AddObserver(HostScanScheduler* host_scan_scheduler) override;
+    void RemoveObserver(HostScanScheduler* host_scan_scheduler) override;
+    bool IsAuthenticatedUserLoggedIn() const override;
+    bool IsNetworkConnectedOrConnecting() const override;
+    bool AreTetherHostsSynced() const override;
+  };
+
+  HostScanScheduler(std::unique_ptr<Context> context_,

[Tim Song, 2016/12/17 05:13:41]

nit: no trailing underscore.

[Kyle Horimoto, 2016/12/19 21:10:47]

Done.

+                    std::unique_ptr<HostScanner> host_scanner);
+
+  std::unique_ptr<Context> context_;
+  std::unique_ptr<HostScanner> host_scanner_;
+  bool initialized_;
+
+  DISALLOW_COPY_AND_ASSIGN(HostScanScheduler);
+};
+
+}  // namespace tether
+
+}  // namespace chromeos
+
+#endif  // CHROMEOS_COMPONENTS_TETHER_HOST_SCAN_SCHEDULER_H