[Wi-Fi] Quit worker thread in WifiNetworkListFragment

Should quit worker thread when a fragment is about to
be destroyed.

Bug: 145100890
Test: make RunSettingsRoboTests ROBOTEST_FILTER=WifiNetworkListFragmentTest
Change-Id: I840750ac4e9601fe553ce219305876581bea7197

src/com/android/settings/wifi/dpp/WifiNetworkListFragment.java

@@ -73,7 +73,7 @@ public class WifiNetworkListFragment extends SettingsPreferenceFragment implemen
     private static final long SCAN_INTERVAL_MILLIS = 10_000;
 
     @VisibleForTesting SavedNetworkTracker mSavedNetworkTracker;
-    private HandlerThread mWorkerThread;
+    @VisibleForTesting HandlerThread mWorkerThread;
 
     // Container Activity must implement this interface
     public interface OnChooseNetworkListener {
@@ -158,6 +158,13 @@ public class WifiNetworkListFragment extends SettingsPreferenceFragment implemen
                 this);
     }
 
+    @Override
+    public void onDestroyView() {
+        mWorkerThread.quit();
+
+        super.onDestroyView();
+    }
+
     @Override
     public void onActivityResult(int requestCode, int resultCode, Intent data) {
         super.onActivityResult(requestCode, resultCode, data);

tests/robotests/src/com/android/settings/wifi/dpp/WifiNetworkListFragmentTest.java

@@ -30,6 +30,7 @@ import android.content.Context;
 import android.content.Intent;
 import android.net.wifi.WifiConfiguration;
 import android.net.wifi.WifiManager;
+import android.os.HandlerThread;
 
 import androidx.preference.Preference;
 import androidx.preference.PreferenceCategory;
@@ -139,4 +140,17 @@ public class WifiNetworkListFragmentTest {
 
         verify(mWifiNetworkListFragment.mOnChooseNetworkListener).onChooseNetwork(any());
     }
+
+    @Test
+    public void onDestroy_quitWorkerThread() {
+        mWifiNetworkListFragment.mWorkerThread = mock(HandlerThread.class);
+
+        try {
+            mWifiNetworkListFragment.onDestroyView();
+        } catch (IllegalArgumentException e) {
+            // Ignore the exception from super class.
+        }
+
+        verify(mWifiNetworkListFragment.mWorkerThread).quit();
+    }
 }