Setting content description when illustration is clickable

Test: Built and tested with other cls in topic and verified talkback works properly.

Flag: None

Bug: 319747547

Change-Id: I37cbcc9bc4c830c73913cdad0734a874bd0eac7c

src/com/android/settings/gestures/SystemNavigationGestureSettings.java

@@ -247,6 +247,7 @@ public class SystemNavigationGestureSettings extends RadioButtonPickerFragment i
         switch (systemNavKey) {
             case KEY_SYSTEM_NAV_GESTURAL:
                 if (isGestureTutorialAvailable()){
+                    videoPref.setContentDescription(R.string.nav_tutorial_button_description);
                     videoPref.setOnPreferenceClickListener(preference -> {
                         startActivity(mLaunchSandboxIntent);
                         return true;