title: Connect with Google Drive without add account to android.accounts.AccountManager?
body: <p>please tell me whether it is possible?
  I will connect to google drive, but I do not want to add an account to android AccountManager.</p>
  
  <pre><code>        credential = GoogleAccountCredential.usingOAuth2(
              activity, Arrays.asList(SCOPES))
              .setBackOff(new ExponentialBackOff())
              .setSelectedAccountName(PREF_ACCOUNT_NAME);
  </code></pre>
  
  <p>It does not work because my account is not added to android.accounts.AccountManager.</p>
  
  <p>I do not want to show the user with which account the application is connected and where taking files.</p>
  
  <p>Thanks</p>