Add visibility metrics to dialogs.

Bug: 30681529
Test: adb logcat -b events | egrep "(sysui_|notification_)"
Change-Id: I199d2e1b2cb8588a562b46bb8128d8ece24952f0

src/com/android/settings/wifi/WifiScanModeActivity.java

@@ -28,7 +28,9 @@ import android.net.wifi.WifiManager;
 import android.os.Bundle;
 import android.provider.Settings;
 
+import com.android.internal.logging.MetricsProto;
 import com.android.settings.R;
+import com.android.settings.core.instrumentation.InstrumentedDialogFragment;
 
 /**
  * This activity requests users permission to allow scanning even when Wi-Fi is turned off
@@ -104,7 +106,7 @@ public class WifiScanModeActivity extends Activity {
         createDialog();
     }
 
-    public static class AlertDialogFragment extends DialogFragment {
+    public static class AlertDialogFragment extends InstrumentedDialogFragment {
         static AlertDialogFragment newInstance(String app) {
             AlertDialogFragment frag = new AlertDialogFragment(app);
             return frag;
@@ -121,6 +123,11 @@ public class WifiScanModeActivity extends Activity {
             mApp = null;
         }
 
+        @Override
+        public int getMetricsCategory() {
+            return MetricsProto.MetricsEvent.DIALOG_WIFI_SCAN_MODE;
+        }
+
         @Override
         public Dialog onCreateDialog(Bundle savedInstanceState) {
             return new AlertDialog.Builder(getActivity())