Tether: only scan when asked to by NetworkStateHandler.

chromeos/components/tether/host_scanner.cc

 // Copyright 2014 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_scanner.h"
 
 #include <algorithm>
 
 #include "base/bind.h"
 #include "chromeos/components/tether/device_id_tether_network_guid_map.h"
@@ skipping 22 matching lines @@
 
 }  // namespace
 
 HostScanner::HostScanner(
     TetherHostFetcher* tether_host_fetcher,
     BleConnectionManager* connection_manager,
     HostScanDevicePrioritizer* host_scan_device_prioritizer,
     TetherHostResponseRecorder* tether_host_response_recorder,
     NotificationPresenter* notification_presenter,
     DeviceIdTetherNetworkGuidMap* device_id_tether_network_guid_map,
-    HostScanCache* host_scan_cache)
+    HostScanCache* host_scan_cache,
+    base::Clock* clock)
     : tether_host_fetcher_(tether_host_fetcher),
       connection_manager_(connection_manager),
       host_scan_device_prioritizer_(host_scan_device_prioritizer),
       tether_host_response_recorder_(tether_host_response_recorder),
       notification_presenter_(notification_presenter),
       device_id_tether_network_guid_map_(device_id_tether_network_guid_map),
       host_scan_cache_(host_scan_cache),
+      clock_(clock),
       is_fetching_hosts_(false),
       weak_ptr_factory_(this) {}
 
 HostScanner::~HostScanner() {}
 
+bool HostScanner::IsScanActive() {
+  return is_fetching_hosts_ || host_scanner_operation_;
+}
+
+bool HostScanner::HasRecentlyScanned() {
+  if (previous_scan_time_.is_null())
+    return false;
+
+  base::TimeDelta difference = clock_->Now() - previous_scan_time_;
+  return difference.InMinutes() <
+         HostScanCache::kNumMinutesBeforeCacheEntryExpires;
+}
+
 void HostScanner::StartScan() {
-  if (host_scanner_operation_) {
-    // If a scan is already active, do not continue.
+  if (IsScanActive()) {
     return;
   }
 
-  if (is_fetching_hosts_) {
-    // If fetching tether hosts is active, stop and wait for them to load.
-    return;
-  }
   is_fetching_hosts_ = true;
-
   tether_host_fetcher_->FetchAllTetherHosts(base::Bind(
       &HostScanner::OnTetherHostsFetched, weak_ptr_factory_.GetWeakPtr()));
 }
 
-bool HostScanner::IsScanActive() {
-  return is_fetching_hosts_ || host_scanner_operation_;
-}
-
 void HostScanner::OnTetherHostsFetched(
     const cryptauth::RemoteDeviceList& tether_hosts) {
   is_fetching_hosts_ = false;
 
   host_scanner_operation_ = HostScannerOperation::Factory::NewInstance(
       tether_hosts, connection_manager_, host_scan_device_prioritizer_,
       tether_host_response_recorder_);
   host_scanner_operation_->AddObserver(this);
   host_scanner_operation_->Initialize();
 }
@@ skipping 19 matching lines @@
     } else {
       notification_presenter_->NotifyMultiplePotentialHotspotsNearby();
     }
   }
 
   if (is_final_scan_result) {
     // If the final scan result has been received, the operation is finished.
     // Delete it.
     host_scanner_operation_->RemoveObserver(this);
     host_scanner_operation_.reset();
+    NotifyScanFinished();
+    previous_scan_time_ = clock_->Now();
   }
 }
 
+void HostScanner::AddObserver(Observer* observer) {
+  observer_list_.AddObserver(observer);
+}
+
+void HostScanner::RemoveObserver(Observer* observer) {
+  observer_list_.RemoveObserver(observer);
+}
+
+void HostScanner::NotifyScanFinished() {
+  for (auto& observer : observer_list_) {
+    observer.ScanFinished();
+  }
+}
+
 void HostScanner::SetCacheEntry(
     const HostScannerOperation::ScannedDeviceInfo& scanned_device_info) {
   const DeviceStatus& status = scanned_device_info.device_status;
   const cryptauth::RemoteDevice& remote_device =
       scanned_device_info.remote_device;
 
   // Use a sentinel value if carrier information is not available. This value is
   // special-cased and replaced with a localized string in the settings UI.
   const std::string carrier =
       (!status.has_cell_provider() || status.cell_provider().empty())
@@ skipping 17 matching lines @@
 
   host_scan_cache_->SetHostScanResult(
       device_id_tether_network_guid_map_->GetTetherNetworkGuidForDeviceId(
           remote_device.GetDeviceId()),
       remote_device.name, carrier, battery_percentage, signal_strength);
 }
 
 }  // namespace tether
 
 }  // namespace chromeos