[CrOS Tether] Create HostScanCache, which caches scan results and inserts them into the network sta…

chromeos/components/tether/host_scanner.h

 // 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_SCANNER_H_
 #define CHROMEOS_COMPONENTS_TETHER_HOST_SCANNER_H_
 
 #include <vector>
 
 #include "base/memory/weak_ptr.h"
 #include "chromeos/components/tether/host_scanner_operation.h"
 #include "chromeos/components/tether/notification_presenter.h"
 #include "chromeos/network/network_state_handler.h"
 #include "components/cryptauth/remote_device.h"
 
 namespace chromeos {
 
 namespace tether {
 
 class BleConnectionManager;
 class DeviceIdTetherNetworkGuidMap;
+class HostScanCache;
 class HostScanDevicePrioritizer;
 class TetherHostFetcher;
 class TetherHostResponseRecorder;
 
-// Scans for nearby tether hosts.
-// TODO(khorimoto): Add some sort of "staleness" timeout which removes scan
-//                  results which occurred long enough ago that they are no
-//                  longer valid.
+// Scans for nearby tether hosts. When StartScan() is called, this class creates
+// a new HostScannerOperation and uses it to contact nearby devices to query
+// whether they can provide tether capabilities. Once the scan results are
+// received, they are stored in the HostScanCache passed to the constructor.
 class HostScanner : public HostScannerOperation::Observer {
  public:
   HostScanner(TetherHostFetcher* tether_host_fetcher,
               BleConnectionManager* connection_manager,
               HostScanDevicePrioritizer* host_scan_device_prioritizer,
               TetherHostResponseRecorder* tether_host_response_recorder,
-              NetworkStateHandler* network_state_handler,
               NotificationPresenter* notification_presenter,
-              DeviceIdTetherNetworkGuidMap* device_id_tether_network_guid_map);
+              DeviceIdTetherNetworkGuidMap* device_id_tether_network_guid_map,
+              HostScanCache* host_scan_cache);
   virtual ~HostScanner();
 
   // Starts a host scan if there is no current scan. If a scan is ongoing, this
   // function is a no-op.
   virtual void StartScan();
 
   bool IsScanActive();
 
-  std::vector<HostScannerOperation::ScannedDeviceInfo>
-  most_recent_scan_results() {
-    return most_recent_scan_results_;
-  }
-
   // HostScannerOperation::Observer:
   void OnTetherAvailabilityResponse(
       std::vector<HostScannerOperation::ScannedDeviceInfo>&
           scanned_device_list_so_far,
       bool is_final_scan_result) override;
 
  private:
   friend class HostScannerTest;
   friend class HostScanSchedulerTest;
 
   void OnTetherHostsFetched(const cryptauth::RemoteDeviceList& tether_hosts);
+  void SetCacheEntry(
+      const HostScannerOperation::ScannedDeviceInfo& scanned_device_info);
 
   TetherHostFetcher* tether_host_fetcher_;
   BleConnectionManager* connection_manager_;
   HostScanDevicePrioritizer* host_scan_device_prioritizer_;
   TetherHostResponseRecorder* tether_host_response_recorder_;
-  NetworkStateHandler* network_state_handler_;
   NotificationPresenter* notification_presenter_;
   DeviceIdTetherNetworkGuidMap* device_id_tether_network_guid_map_;
+  HostScanCache* host_scan_cache_;
 
   bool is_fetching_hosts_;
   std::unique_ptr<HostScannerOperation> host_scanner_operation_;
-  std::vector<HostScannerOperation::ScannedDeviceInfo>
-      most_recent_scan_results_;
 
   base::WeakPtrFactory<HostScanner> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(HostScanner);
 };
 
 }  // namespace tether
 
 }  // namespace chromeos
 
 #endif  // CHROMEOS_COMPONENTS_TETHER_HOST_SCANNER_H_