Android : DriveScopes cannot be resolved to a variable.

i am facing the problem in Drive. I am unable to import it. please help me to resolve it thanks private ProgressBar progressBar; private Context context; private static Uri callLogFileUri; private static Uri smsLogFileUri; private static Drive service; private boolean callLogs; private boolean smsLogs; private String address; private ContentResolver cr; private GoogleAccountCredential credential;

@Override
public void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.backup_layout);

  progressBar = (ProgressBar) findViewById(R.id.progressBar);
  progressBar.setVisibility(View.VISIBLE);

  context = this;
  Intent intent;
  cr = getContentResolver();
  credential = GoogleAccountCredential.usingOAuth2(this,DriveScopes.DRIVE);

  try {
      intent = getIntent();

      if (intent.hasExtra("fromReceiver")) {
          address = intent.getStringExtra("fromReceiver");
          Log.i(TAG, "Backup intent from receiver");
          recoverData();
      } else {
          Log.i(TAG, "Backup intent from elsewhere");
          DialogFragment dialog = new BackupAccountsDialogFragment();
          dialog.show(getFragmentManager(),
                  "BackupAccountsDialogFragment");
      }

  } catch(Exception e) {
      recoverData();
  }
}

@Override
protected void onActivityResult(final int requestCode, final int resultCode, final Intent data) {
  switch (requestCode) {
  case REQUEST_ACCOUNT_PICKER:
    if (resultCode == RESULT_OK && data != null && data.getExtras() != null) {
      final String accountName = data.getStringExtra(AccountManager.KEY_ACCOUNT_NAME);
      if (accountName != null) {
        Log.i(TAG, "REQUEST ACCOUNT PICKER");
        credential.setSelectedAccountName(accountName);
        service = getDriveService(credential);
        storeGoogleAccounts(accountName);
        Log.i(TAG, "Account saved: " + CHOSEN_GOOGLE_ACCOUNT + " " + accountName);
        getFirstAuthInAsync();
      }