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

chromeos/components/tether/host_scanner.h

Index: chromeos/components/tether/host_scanner.h
diff --git a/chromeos/components/tether/host_scanner.h b/chromeos/components/tether/host_scanner.h
index 1913a980eae7afb97099daa464122431ef118dad..85e1ef77c9fdaeaff8c6e99fa0a76c0a99b1cc38 100644
--- a/chromeos/components/tether/host_scanner.h
+++ b/chromeos/components/tether/host_scanner.h
@@ -19,23 +19,24 @@ 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
@@ -44,11 +45,6 @@ class HostScanner : public HostScannerOperation::Observer {
 
   bool IsScanActive();
 
-  std::vector<HostScannerOperation::ScannedDeviceInfo>
-  most_recent_scan_results() {
-    return most_recent_scan_results_;
-  }
-
   // HostScannerOperation::Observer:
   void OnTetherAvailabilityResponse(
       std::vector<HostScannerOperation::ScannedDeviceInfo>&
@@ -60,19 +56,19 @@ class HostScanner : public HostScannerOperation::Observer {
   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_;