Fix restore page back navigation

Issue: calyxos#2284
Change-Id: I72249924d4b0c56b6bcceea1c5a4adbfa5c54fb2
diff --git a/src/org/lineageos/setupwizard/backup/RestoreIntroActivity.java b/src/org/lineageos/setupwizard/backup/RestoreIntroActivity.java
index f7abe31..b43798b 100644
--- a/src/org/lineageos/setupwizard/backup/RestoreIntroActivity.java
+++ b/src/org/lineageos/setupwizard/backup/RestoreIntroActivity.java
@@ -6,8 +6,12 @@
 
 package org.lineageos.setupwizard.backup;
 
+import static com.google.android.setupcompat.util.ResultCodes.RESULT_ACTIVITY_NOT_FOUND;
+
 import static org.lineageos.setupwizard.SetupWizardApp.ACTION_RESTORE_FROM_BACKUP;
 
+import androidx.activity.result.ActivityResult;
+
 import android.content.Intent;
 import android.os.Bundle;
 
@@ -24,6 +28,19 @@
     }
 
     @Override
+    protected void onActivityResult(ActivityResult activityResult) {
+        int resultCode = activityResult.getResultCode();
+        Intent data = activityResult.getData();
+        if (resultCode != RESULT_CANCELED) {
+            nextAction(resultCode, data);
+        } else if (mIsSubactivityNotFound) {
+            finishAction(RESULT_ACTIVITY_NOT_FOUND);
+        } else if (data != null && data.getBooleanExtra("onBackPressed", false)) {
+            onStartSubactivity();
+        }
+    }
+
+    @Override
     protected void onStartSubactivity() {
         setNextAllowed(true);
     }