[CrOS Tether] Sort Tether network lists.

chromeos/components/tether/host_scan_device_prioritizer.cc

-// 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.
-
-#include "chromeos/components/tether/host_scan_device_prioritizer.h"
-
-#include "base/memory/ptr_util.h"
-#include "base/values.h"
-#include "chromeos/components/tether/pref_names.h"
-#include "chromeos/components/tether/tether_host_response_recorder.h"
-#include "components/prefs/pref_registry_simple.h"
-#include "components/prefs/pref_service.h"
-
-namespace chromeos {
-
-namespace tether {
-
-HostScanDevicePrioritizer::HostScanDevicePrioritizer(
-    TetherHostResponseRecorder* tether_host_response_recorder)
-    : tether_host_response_recorder_(tether_host_response_recorder) {}
-
-HostScanDevicePrioritizer::~HostScanDevicePrioritizer() {}
-
-void HostScanDevicePrioritizer::SortByHostScanOrder(
-    std::vector<cryptauth::RemoteDevice>* remote_devices) const {
-  // First, fetch the hosts which have previously responded.
-  std::vector<std::string> prioritized_ids =
-      tether_host_response_recorder_->GetPreviouslyAvailableHostIds();
-
-  std::vector<std::string> previously_connectable_host_ids =
-      tether_host_response_recorder_->GetPreviouslyConnectedHostIds();
-  if (!previously_connectable_host_ids.empty()) {
-    // If there is a most-recently connectable host, insert it at the front of
-    // the list.
-    prioritized_ids.insert(prioritized_ids.begin(),
-                           previously_connectable_host_ids[0]);
-  }
-
-  // Iterate from the last stored ID to the first stored ID. This ensures that
-  // the items at the front of the list end up in the front of the prioritized
-  // |remote_devices| vector.
-  for (auto prioritized_it = prioritized_ids.rbegin();
-       prioritized_it != prioritized_ids.rend(); ++prioritized_it) {
-    // Iterate through |remote_devices| to see if a device exists with a
-    // device ID of |stored_id|. If one exists, remove it from its previous
-    // position in the list and add it at the front instead.
-    for (auto remote_devices_it = remote_devices->begin();
-         remote_devices_it != remote_devices->end(); ++remote_devices_it) {
-      if (remote_devices_it->GetDeviceId() != *prioritized_it) {
-        continue;
-      }
-
-      cryptauth::RemoteDevice device_to_move = *remote_devices_it;
-      remote_devices->erase(remote_devices_it);
-      remote_devices->insert(remote_devices->begin(), device_to_move);
-      break;
-    }
-  }
-}
-
-}  // namespace tether
-
-}  // namespace chromeos