send email with google client php sdk

$client = new Google_Client();
// Get your credentials from the console
$client->setClientId('YOUR_CLIENT_ID');
$client->setClientSecret('YOUR_CLIENT_SECRET');
$client->setRedirectUri('YOUR_REGISTERED_REDIRECT_URI');
$client->setScopes(array('https://www.googleapis.com/auth/gmail.compose'));

$service = new Google_Service_Gmail($client);

$message = new Google_Service_Gmail_Message();
$message->setRaw(strtr(base64_encode($mime), '+/', '-_'));
$service->users_messages->send('me', $message);