Google+ sign out à partir d'une autre activité

J'ai commencé à utiliser le Google+ API pour android, et j'ai créé un signe-dans l'application en suivant ce tutoriel:

https://developers.google.com/+/mobile/android/connexion

Maintenant, le problème est que je veux créer le bouton de déconnexion à partir d'un autre Activity, et ce que j'ai essayé de faire n'a pas vraiment fonctionné..

Mon GPlusLogin (code de l'Activité pour Google+ Login):

import android.app.Activity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.content.IntentSender.SendIntentException;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import com.google.android.gms.common.*;
import com.google.android.gms.common.GooglePlayServicesClient.ConnectionCallbacks;
import com.google.android.gms.common.GooglePlayServicesClient.OnConnectionFailedListener;
import com.google.android.gms.plus.PlusClient;
public class GPlusLogin extends Activity implements ConnectionCallbacks, OnConnectionFailedListener{
private static final int REQUEST_CODE_RESOLVE_ERR = 9000;
private static final String TAG = "GPlusLogin";
private ProgressDialog mConnectionProgressDialog;
private PlusClient mPlusClient;
private ConnectionResult mConnectionResult;
@Override
protected void onCreate(Bundle savedInstanceState) {
//TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.gplus_layout);
mPlusClient = new PlusClient.Builder(this, this, this).setVisibleActivities("http://schemas.google.com/AddActivity", "http://schemas.google.com/BuyActivity").build();
Bundle extras = getIntent().getExtras();
mConnectionProgressDialog = new ProgressDialog(this);
mConnectionProgressDialog.setMessage("Signing in...");
if(extras!=null){
if(extras.getString("signout")!=null){
if (mPlusClient.isConnected()) {
mPlusClient.clearDefaultAccount();
mPlusClient.disconnect();
mPlusClient.connect();
finish();
startActivity(getIntent());
}
}
}else{
findViewById(R.id.sign_in_button).setOnClickListener(new OnClickListener() {
public void onClick(View view) {
//TODO Auto-generated method stub
if (view.getId() == R.id.sign_in_button && !mPlusClient.isConnected()) {
if (mConnectionResult == null) {
mConnectionProgressDialog.show();
} else {
try {
mConnectionResult.startResolutionForResult(GPlusLogin.this, REQUEST_CODE_RESOLVE_ERR);
} catch (SendIntentException e) {
//Try connecting again.
mConnectionResult = null;
mPlusClient.connect();
}
}
}
}
});
}
}
@Override
protected void onStart() {
//TODO Auto-generated method stub
super.onStart();
mPlusClient.connect();
}
@Override
protected void onStop() {
//TODO Auto-generated method stub
super.onStop();
mPlusClient.disconnect();
}
@Override
public void onConnectionFailed(ConnectionResult result) {
//TODO Auto-generated method stub
if (mConnectionProgressDialog.isShowing()) {
//The user clicked the sign-in button already. Start to resolve
//connection errors. Wait until onConnected() to dismiss the
//connection dialog.
if (result.hasResolution()) {
try {
result.startResolutionForResult(this, REQUEST_CODE_RESOLVE_ERR);
} catch (SendIntentException e) {
mPlusClient.connect();
}
}
}
mConnectionResult = result;
}
@Override
protected void onActivityResult(int requestCode, int responseCode, Intent intent) {
if (requestCode == REQUEST_CODE_RESOLVE_ERR && responseCode == RESULT_OK) {
mConnectionResult = null;
mPlusClient.connect();
}
}
@Override
public void onConnected() {
//TODO Auto-generated method stub
mConnectionProgressDialog.dismiss();
Intent main = new Intent(GPlusLogin.this, MainActivity.class);
main.putExtra("result", true);
startActivity(main);
}
@Override
public void onDisconnected() {
//TODO Auto-generated method stub
Log.d(TAG, "disconnected");
}
}

Mon Débranchez le code sur MainActivity:

import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
public class MainActivity extends Activity{
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Bundle extras = getIntent().getExtras();
if(extras==null){
Intent intent = new Intent(this, GPlusLogin.class);
startActivity(intent);
}
TextView text1 = (TextView) findViewById(R.id.text1);
text1.setText("You Are Connected :D");
Button SignOut = (Button) findViewById(R.id.sign_out_gplus);
SignOut.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View view) {
//TODO Auto-generated method stub
Intent intent = new Intent(MainActivity.this, GPlusLogin.class);
intent.putExtra("signout", true);
startActivity(intent);
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
//Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}