Settings: Hide the nav bar during udfps fp enrolling

On some devices, udfps is kinda near to nav bar
so the enroll circle ends up behind the nav bar
and that looks not good.

Change-Id: I5184f8e8c34693d145199c2081e543656d8d702c
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>

src/com/android/settings/biometrics/fingerprint/FingerprintEnrollEnrolling.java

@@ -355,6 +355,20 @@ public class FingerprintEnrollEnrolling extends BiometricsEnrollEnrolling {
         }
     }
 
+    @Override
+    protected void onResume() {
+        super.onResume();
+        // Ignore if it's not udfps.
+        if (!mCanAssumeUdfps) {
+            return;
+        }
+        View decorView = getWindow().getDecorView();
+        // Hide the navigation bar and make the layout stable.
+        // so that the content doesn't resize as the navigation bar hides and shows.
+        int uiOptions = View.SYSTEM_UI_FLAG_HIDE_NAVIGATION | View.SYSTEM_UI_FLAG_LAYOUT_STABLE;
+        decorView.setSystemUiVisibility(uiOptions);
+    }
+
     private void setHelpAnimation() {
         final RelativeLayout progressLottieLayout = findViewById(R.id.progress_lottie);
         mHelpAnimation = mSfpsEnrollmentFeature.getHelpAnimator(progressLottieLayout);