Как получить доступ к новому API Gmail из моего приложения для Android?

Я пытаюсь получить доступ к новому API Gmail (объявлено 25.06.2014) из моего приложения для Android, чтобы вернуть все сообщения электронной почты в определенной учетной записи пользователя. Я разрабатываю приложение в Eclipse с помощью подключаемого модуля ADT.
Что я сделал до сих пор:

• Я зарегистрировал приложение в Google Developers Console
  (ссылка: console.developers.google.com/project).

• Я внедрил кнопку входа в Google+ (ссылка: developers.google.com/+/mobile/android/sign-in). Кнопка входа в Google+ проверяет подлинность пользователя и управляет потоком OAuth 2.0, что упрощает интеграцию с API Google.

• Я добавил дополнительную область "https://www.googleapis.com/auth/gmail.readonly" в Google+ Authorization для доступа к API Gmail, как указано в
  (Ссылка: developers.google.com/gmail/api/v1/reference/users/threads/list).

В этот момент у меня есть инициализированный объект GoogleApiClient.

Объект GoogleApiClient переносит ServiceConnection (ссылка: developer.android.com/reference/android/content/ServiceConnection.html) в службы Google Play. Объект GoogleApiClient используется для связи с API Google+ и становится работоспособным после установления асинхронного соединения с сервисом, что указывает на то, что:

• Службы Google Play запущены на устройстве, и приложение Activity успешно связало сервисное соединение,
• пользователь выбрал учетную запись, которую они хотят использовать с приложением, и
• учетная запись пользователя предоставила разрешения, запрашиваемые приложением.

Как мне перейти сюда, чтобы получить все сообщения с этим httprequest?
Я попытался получить доступ к API Gmail на этом этапе, но я получаю ошибку аутентификации 401: требуется вход в систему, даже если логин Google+ был успешным, и я успешно вернул список пользовательских кругов.

EDIT: SecondActivity.java

import android.app.Activity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;

import com.google.android.gms.auth.GoogleAuthException;
import com.google.android.gms.auth.GoogleAuthUtil;
import com.google.android.gms.auth.GooglePlayServicesAvailabilityException;
import com.google.android.gms.auth.UserRecoverableAuthException;
import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.GooglePlayServicesUtil;
import com.google.android.gms.common.SignInButton;
import com.google.android.gms.common.api.CommonStatusCodes;
import com.google.android.gms.common.api.GoogleApiClient;
import com.google.android.gms.common.api.GoogleApiClient.ConnectionCallbacks;
import com.google.android.gms.common.api.GoogleApiClient.OnConnectionFailedListener;
import com.google.android.gms.common.api.ResultCallback;
import com.google.android.gms.common.api.Scope;
import com.google.android.gms.plus.People;
import com.google.android.gms.plus.People.LoadPeopleResult;
import com.google.android.gms.plus.Plus;
import com.google.android.gms.plus.model.people.Person;
import com.google.android.gms.plus.model.people.PersonBuffer;
import com.google.api.services.gmail.Gmail;
import com.google.api.services.gmail.Gmail.Users;
import com.google.api.services.gmail.Gmail.Users.Messages.GmailImport;
import com.google.api.services.gmail.GmailRequest;
import com.google.api.services.gmail.GmailRequestInitializer;
import com.google.api.services.gmail.GmailScopes;

import android.app.AlertDialog;
import android.app.Dialog;
import android.app.PendingIntent;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.IntentSender.SendIntentException;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.support.v7.app.ActionBarActivity;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;
import mk.ukim.feit.recognizer.application.PeopleAdapter;
import mk.ukim.feit.recognizer.interfaces.GetMessages;
import mk.ukim.feit.recognizer.tasks.GetMessagesTask;
import mk.ukim.feit.recognizer.util.MyClass;
import mk.ukim.feit.recognizer.util.exception.FaceClientException;
import mk.ukim.feit.recognizer.util.model.Face;
import mk.ukim.feit.recognizer.util.model.Guess;
import mk.ukim.feit.recognizer.util.model.Photo;
import mk.ukim.feit.recognizer.util.response.PhotoResponse;
import mk.ukim.feit.recognizer.util.response.PhotoResponseImpl;

import java.io.IOException;
import java.util.ArrayList;


public class SecondActivity extends FragmentActivity implements
    GetMessages, ConnectionCallbacks, OnConnectionFailedListener,
    ResultCallback<People.LoadPeopleResult>, View.OnClickListener {

  private static final String TAG = "android-plus-quickstart";

  private static final int STATE_DEFAULT = 0;
  private static final int STATE_SIGN_IN = 1;
  private static final int STATE_IN_PROGRESS = 2;

  private static final int RC_SIGN_IN = 0;
  private static final int MY_ACTIVITYS_AUTH_REQUEST_CODE=045;

  private static final int DIALOG_PLAY_SERVICES_ERROR = 0;

  private static final String SAVED_PROGRESS = "sign_in_progress";

  private GoogleApiClient mGoogleApiClient;
  String name; 

  private PendingIntent mSignInIntent;
  private int mSignInError;
  private SignInButton mSignInButton;
  private Button mSignOutButton;
  private Button mRevokeButton;
  private TextView mStatus;
  private ListView mCirclesListView;
  private ArrayAdapter<String> mCirclesAdapter;
  private ArrayList<String> mCirclesList;

  public Scope gmail=new Scope("https://www.googleapis.com/auth/gmail.readonly");
  String scope="https://www.googleapis.com/auth/gmail.readonly";
  String email="[email protected]";



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

    Intent intent = getIntent();
    name="Team";

    mSignInButton = (SignInButton) findViewById(R.id.sign_in_button);
    mSignOutButton = (Button) findViewById(R.id.sign_out_button);
    mRevokeButton = (Button) findViewById(R.id.revoke_access_button);
    mStatus = (TextView) findViewById(R.id.sign_in_status);
    mCirclesListView = (ListView) findViewById(R.id.circles_list);

    mSignInButton.setOnClickListener(this);
    mSignOutButton.setOnClickListener(this);
    mRevokeButton.setOnClickListener(this);

    mCirclesList = new ArrayList<String>();
    mCirclesAdapter = new ArrayAdapter<String>(
        this, R.layout.circle_member, mCirclesList);
    mCirclesListView.setAdapter(mCirclesAdapter);

    if (savedInstanceState != null) {
      mSignInProgress = savedInstanceState
          .getInt(SAVED_PROGRESS, STATE_DEFAULT);

    }

    mGoogleApiClient = buildGoogleApiClient();
  }



private GoogleApiClient buildGoogleApiClient() {
    return new GoogleApiClient.Builder(this)
        .addConnectionCallbacks(this)
        .addOnConnectionFailedListener(this)
        .addApi(Plus.API, Plus.PlusOptions.builder().build())
        .addScope(Plus.SCOPE_PLUS_LOGIN)
        .addScope(gmail)
        .build();
  }

@Override
  protected void onStart() {
    super.onStart();
    mGoogleApiClient.connect();
    getAndUseAuthTokenInAsyncTask();
  }



@Override
  protected void onStop() {
    super.onStop();

    if (mGoogleApiClient.isConnected()) {
      mGoogleApiClient.disconnect();
    }
  }

  @Override
  protected void onSaveInstanceState(Bundle outState) {
    super.onSaveInstanceState(outState);
    outState.putInt(SAVED_PROGRESS, mSignInProgress);
  }



@Override
  public void onClick(View v) {
    if (!mGoogleApiClient.isConnecting()) {
          switch (v.getId()) {
          case R.id.sign_in_button:
            mStatus.setText(R.string.status_signing_in);
            resolveSignInError();
            break;
          case R.id.sign_out_button:
            Plus.AccountApi.clearDefaultAccount(mGoogleApiClient);
            mGoogleApiClient.disconnect();
            mGoogleApiClient.connect();
            break;
          case R.id.revoke_access_button:
            Plus.AccountApi.clearDefaultAccount(mGoogleApiClient);
            Plus.AccountApi.revokeAccessAndDisconnect(mGoogleApiClient);
            mGoogleApiClient = buildGoogleApiClient();
            mGoogleApiClient.connect();
            break;
      }
    }
  }

  @Override
  public void onConnected(Bundle connectionHint) {
    Log.i(TAG, "onConnected");

    getAndUseAuthTokenInAsyncTask();

    mSignInButton.setEnabled(false);
    mSignOutButton.setEnabled(true);
    mRevokeButton.setEnabled(true);

    // Retrieve some profile information. This is OK
    Person currentUser = Plus.PeopleApi.getCurrentPerson(mGoogleApiClient);
    String klient=mGoogleApiClient.toString();


    mStatus.setText(String.format(
        getResources().getString(R.string.signed_in_as),
        currentUser.getDisplayName()));


    Plus.PeopleApi.loadVisible(mGoogleApiClient, null)
        .setResultCallback(this);

    GetMessagesTask task = new GetMessagesTask(
            SecondActivity.this, name, mGoogleApiClient);
        task.setDelegate(SecondActivity.this);
        task.execute();

    // Indicate that the sign in process is complete.
    mSignInProgress = STATE_DEFAULT;

  }

  @Override
  public void onConnectionFailed(ConnectionResult result) {
    // Refer to the javadoc for ConnectionResult to see what error codes might
    // be returned in onConnectionFailed.
    Log.i(TAG, "onConnectionFailed: ConnectionResult.getErrorCode() = "
        + result.getErrorCode());

    if (mSignInProgress != STATE_IN_PROGRESS) {
      mSignInIntent = result.getResolution();
      mSignInError = result.getErrorCode();

      if (mSignInProgress == STATE_SIGN_IN) {
        // STATE_SIGN_IN indicates the user already clicked the sign in button
        // so we should continue processing errors until the user is signed in
        // or they click cancel.
        resolveSignInError();
      }
    }

    onSignedOut();
  }


  private void resolveSignInError() {
    if (mSignInIntent != null) {

      try {
        mSignInProgress = STATE_IN_PROGRESS;
        startIntentSenderForResult(mSignInIntent.getIntentSender(),
            RC_SIGN_IN, null, 0, 0, 0);
      } catch (SendIntentException e) {
        Log.i(TAG, "Sign in intent could not be sent: "
            + e.getLocalizedMessage());
        // The intent was canceled before it was sent.  Attempt to connect to
        // get an updated ConnectionResult.
        mSignInProgress = STATE_SIGN_IN;
        mGoogleApiClient.connect();

      }
    } else {
      // Google Play services wasn't able to provide an intent for some
      // error types, so we show the default Google Play services error
      // dialog which may still start an intent if the
      // user can resolve the issue.
      showDialog(DIALOG_PLAY_SERVICES_ERROR);
    }
  }


  @Override
  public void onResult(LoadPeopleResult peopleData) {
    if (peopleData.getStatus().getStatusCode() == CommonStatusCodes.SUCCESS) {
      mCirclesList.clear();
      PersonBuffer personBuffer = peopleData.getPersonBuffer();
      try {
          int count = personBuffer.getCount();
          for (int i = 0; i < count; i++) {
              mCirclesList.add(personBuffer.get(i).getDisplayName());
          }
      } finally {
          personBuffer.close();
      }

      mCirclesAdapter.notifyDataSetChanged();
    } else {
      Log.e(TAG, "Error requesting visible circles: " + peopleData.getStatus());
    }
  }

  private void onSignedOut() {
    // Update the UI to reflect that the user is signed out.
    mSignInButton.setEnabled(true);
    mSignOutButton.setEnabled(false);
    mRevokeButton.setEnabled(false);

    mStatus.setText(R.string.status_signed_out);

    mCirclesList.clear();
    mCirclesAdapter.notifyDataSetChanged();
  }

  @Override
  public void onConnectionSuspended(int cause) {
    // The connection to Google Play services was lost for some reason.
    // We call connect() to attempt to re-establish the connection or get a
    // ConnectionResult that we can attempt to resolve.
    mGoogleApiClient.connect();
  }

  @Override
  protected Dialog onCreateDialog(int id) {
    switch(id) {
      case DIALOG_PLAY_SERVICES_ERROR:
        if (GooglePlayServicesUtil.isUserRecoverableError(mSignInError)) {
          return GooglePlayServicesUtil.getErrorDialog(
              mSignInError,
              this,
              RC_SIGN_IN,
              new DialogInterface.OnCancelListener() {
                @Override
                public void onCancel(DialogInterface dialog) {
                  Log.e(TAG, "Google Play services resolution cancelled");
                  mSignInProgress = STATE_DEFAULT;
                  mStatus.setText(R.string.status_signed_out);
                }
              });
        } else {
          return new AlertDialog.Builder(this)
              .setMessage(R.string.play_services_error)
              .setPositiveButton(R.string.close,
                  new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                      Log.e(TAG, "Google Play services error could not be "
                          + "resolved: " + mSignInError);
                      mSignInProgress = STATE_DEFAULT;
                      mStatus.setText(R.string.status_signed_out);
                    }
                  }).create();
        }
      default:
        return super.onCreateDialog(id);
    }
  }




    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
           if (requestCode == MY_ACTIVITYS_AUTH_REQUEST_CODE) {
               if (resultCode == RESULT_OK) {
                   getAndUseAuthTokenInAsyncTask();
               }
           }
       }


       public void getAndUseAuthTokenBlocking() throws UserRecoverableAuthException, IOException, GoogleAuthException {

              final String token = GoogleAuthUtil.getToken(this, email, scope);
              String fff="";
        }      


       public void getAndUseAuthTokenInAsyncTask() {

        AsyncTask<Void, Void, Void> task = new AsyncTask<Void,Void, Void>() {


               @Override
               protected Void doInBackground(Void... params) {
                   // TODO Auto-generated method stub
                   try {
                    getAndUseAuthTokenBlocking();
                } catch (UserRecoverableAuthException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                } catch (GoogleAuthException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
                   return null;
               }
           };
           task.execute((Void)null);
       }

    }

ИЗМЕНИТЬ 2: LogCat

07-16 06:44:27.300: E/AndroidRuntime(11875): FATAL EXCEPTION: AsyncTask #2
07-16 06:44:27.300: E/AndroidRuntime(11875): java.lang.RuntimeException: An error occured while executing doInBackground()
07-16 06:44:27.300: E/AndroidRuntime(11875):    at android.os.AsyncTask$3.done(AsyncTask.java:299)
07-16 06:44:27.300: E/AndroidRuntime(11875):    at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:273)
07-16 06:44:27.300: E/AndroidRuntime(11875):    at java.util.concurrent.FutureTask.setException(FutureTask.java:124)
07-16 06:44:27.300: E/AndroidRuntime(11875):    at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:307)
07-16 06:44:27.300: E/AndroidRuntime(11875):    at java.util.concurrent.FutureTask.run(FutureTask.java:137)
07-16 06:44:27.300: E/AndroidRuntime(11875):    at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
07-16 06:44:27.300: E/AndroidRuntime(11875):    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
07-16 06:44:27.300: E/AndroidRuntime(11875):    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
07-16 06:44:27.300: E/AndroidRuntime(11875):    at java.lang.Thread.run(Thread.java:856)
07-16 06:44:27.300: E/AndroidRuntime(11875): Caused by: java.lang.NoClassDefFoundError: com.google.api.client.googleapis.auth.oauth2.GoogleCredential
07-16 06:44:27.300: E/AndroidRuntime(11875):    at mk.ukim.feit.recognizer.GmailLinkGrabberService$getAuthToken.doInBackground(GmailLinkGrabberService.java:104)
07-16 06:44:27.300: E/AndroidRuntime(11875):    at mk.ukim.feit.recognizer.GmailLinkGrabberService$getAuthToken.doInBackground(GmailLinkGrabberService.java:1)
07-16 06:44:27.300: E/AndroidRuntime(11875):    at android.os.AsyncTask$2.call(AsyncTask.java:287)
07-16 06:44:27.300: E/AndroidRuntime(11875):    at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
07-16 06:44:27.300: E/AndroidRuntime(11875):    ... 5 more