Finish biometric enroll screens when backgrounded

Currently, there are some biometric security setting and enrollment
screens which remain open after the user has backgrounded them. This
means that they can later be resumed without requiring the user to
confirm their device credential as normal.

This commit fixes the issue in AOSP by adding logic to the affected
biometric enrollment/setting activities in to finish() with
RESULT_TIMEOUT in onStop(). We don't want to finish() these activities
prematurely if the user is currently in a wizard setup flow, however. In
that case, this commit ensures that the newly added logic will not run.

Test: Pixel 3 - Background at each step of fingerprint enroll => finish
Test: Pixel 3 - Rotate at each step of fingerprint enroll => no finish
Test: Pixel 3 - Proceed though fingerprint setup wizard => no change

Bug: 142544519
Change-Id: I8ec0fa1e30bafe097d9dc82991ff786ebf24844b

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

@@ -133,6 +133,7 @@ public class FingerprintSettings extends SubSettings {
         private Drawable mHighlightDrawable;
         private int mUserId;
         private CharSequence mFooterTitle;
+        private boolean mEnrollClicked;
 
         private static final String TAG_AUTHENTICATE_SIDECAR = "authenticate_sidecar";
         private static final String TAG_REMOVAL_SIDECAR = "removal_sidecar";
@@ -463,6 +464,14 @@ public class FingerprintSettings extends SubSettings {
             }
         }
 
+        @Override
+        public void onStop() {
+            super.onStop();
+            if (!getActivity().isChangingConfigurations() && !mLaunchedConfirm && !mEnrollClicked) {
+                getActivity().finish();
+            }
+        }
+
         @Override
         public void onSaveInstanceState(final Bundle outState) {
             outState.putByteArray(ChooseLockSettingsHelper.EXTRA_KEY_CHALLENGE_TOKEN,
@@ -475,6 +484,7 @@ public class FingerprintSettings extends SubSettings {
         public boolean onPreferenceTreeClick(Preference pref) {
             final String key = pref.getKey();
             if (KEY_FINGERPRINT_ADD.equals(key)) {
+                mEnrollClicked = true;
                 Intent intent = new Intent();
                 intent.setClassName(SETTINGS_PACKAGE_NAME,
                         FingerprintEnrollEnrolling.class.getName());
@@ -564,9 +574,10 @@ public class FingerprintSettings extends SubSettings {
                     }
                 }
             } else if (requestCode == ADD_FINGERPRINT_REQUEST) {
+                mEnrollClicked = false;
                 if (resultCode == RESULT_TIMEOUT) {
                     Activity activity = getActivity();
-                    activity.setResult(RESULT_TIMEOUT);
+                    activity.setResult(resultCode);
                     activity.finish();
                 }
             }