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

chromeos/components/tether/mock_tether_host_response_recorder.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/mock_tether_host_response_recorder.h"
 
 namespace chromeos {
 
 namespace tether {
 
 MockTetherHostResponseRecorder::MockTetherHostResponseRecorder()
     : TetherHostResponseRecorder(nullptr) {}
 
 MockTetherHostResponseRecorder::~MockTetherHostResponseRecorder() {}
 
+void MockTetherHostResponseRecorder::NotifyPreviouslyConnectedHostIdsChanged() {
+  NotifyObserversPreviouslyConnectedHostIdsChanged();
+}
+
 }  // namespace tether
 
 }  // namespace chromeos