Allow choose backup restore flow to work on pre-API29 devices.

app/src/main/java/org/thoughtcrime/securesms/backup/FullBackupImporter.java

@@ -109,7 +109,7 @@ public class FullBackupImporter extends FullBackupBase {
   }
 
   private static @NonNull InputStream getInputStream(@NonNull Context context, @NonNull Uri uri) throws IOException{
-    if (BackupUtil.isUserSelectionRequired(context)) {
+    if (BackupUtil.isUserSelectionRequired(context) || uri.getScheme().equals("content")) {
       return Objects.requireNonNull(context.getContentResolver().openInputStream(uri));
     } else {
       return new FileInputStream(new File(Objects.requireNonNull(uri.getPath())));

app/src/main/java/org/thoughtcrime/securesms/devicetransfer/newdevice/TransferOrRestoreFragment.java

@@ -1,5 +1,6 @@
 package org.thoughtcrime.securesms.devicetransfer.newdevice;
 
+import android.os.Build;
 import android.os.Bundle;
 import android.view.View;
 import android.widget.TextView;
@@ -26,8 +27,12 @@ public final class TransferOrRestoreFragment extends LoggingFragment {
     view.findViewById(R.id.transfer_or_restore_fragment_transfer)
         .setOnClickListener(v -> Navigation.findNavController(v).navigate(R.id.action_new_device_transfer_instructions));
 
-    view.findViewById(R.id.transfer_or_restore_fragment_restore)
-        .setOnClickListener(v -> Navigation.findNavController(v).navigate(R.id.action_choose_backup));
+    View restoreBackup = view.findViewById(R.id.transfer_or_restore_fragment_restore);
+    if (Build.VERSION.SDK_INT >= 21) {
+      restoreBackup.setOnClickListener(v -> Navigation.findNavController(v).navigate(R.id.action_choose_backup));
+    } else {
+      restoreBackup.setVisibility(View.GONE);
+    }
 
     String description = getString(R.string.TransferOrRestoreFragment__transfer_your_account_and_messages_from_your_old_android_device);
     String toBold      = getString(R.string.TransferOrRestoreFragment__you_need_access_to_your_old_device);

app/src/main/java/org/thoughtcrime/securesms/registration/fragments/RestoreBackupFragment.java

@@ -8,6 +8,7 @@ import android.graphics.Canvas;
 import android.graphics.Paint;
 import android.net.Uri;
 import android.os.AsyncTask;
+import android.os.Build;
 import android.os.Bundle;
 import android.text.Editable;
 import android.text.Spanned;
@@ -108,7 +109,7 @@ public final class RestoreBackupFragment extends BaseRegistrationFragment {
     }
 
     RestoreBackupFragmentArgs args = RestoreBackupFragmentArgs.fromBundle(requireArguments());
-    if (BackupUtil.isUserSelectionRequired(requireContext()) && args.getUri() != null) {
+    if ((Build.VERSION.SDK_INT < 29 || BackupUtil.isUserSelectionRequired(requireContext())) && args.getUri() != null) {
       Log.i(TAG, "Restoring backup from passed uri");
       initializeBackupForUri(view, args.getUri());
 
@@ -142,7 +143,6 @@ public final class RestoreBackupFragment extends BaseRegistrationFragment {
     }
   }
 
-  @RequiresApi(29)
   private void initializeBackupForUri(@NonNull View view, @NonNull Uri uri) {
     getFromUri(requireContext(), uri, backup -> handleBackupInfo(view, backup));
   }
@@ -197,7 +197,6 @@ public final class RestoreBackupFragment extends BaseRegistrationFragment {
     }.execute();
   }
 
-  @RequiresApi(29)
   static void getFromUri(@NonNull Context context,
                          @NonNull Uri backupUri,
                          @NonNull OnBackupSearchResultListener listener)

app/src/main/java/org/thoughtcrime/securesms/util/BackupUtil.java

@@ -166,7 +166,6 @@ public class BackupUtil {
     return backups;
   }
 
-  @RequiresApi(29)
   public static @Nullable BackupInfo getBackupInfoFromSingleUri(@NonNull Context context, @NonNull Uri singleUri) {
     DocumentFile documentFile = DocumentFile.fromSingleUri(context, singleUri);