GCM with Android

GCM.php

<?php
public function send_notification($registration_ids, $message) {
    include_once './config.php';
    // Set POST variables
    $url = 'https://android.googleapis.com/gcm/send';
    $fields = array(
        'registration_ids' => $registration_ids,
        'data' => $message,
    );
    $headers = array(
        'Authorization: key=' . GOOGLE_API_KEY,
        'Content-Type: application/json'
    );
    // Open connection
    $ch = curl_init();
    // Set the url, number of POST vars, POST data
    curl_setopt($ch, CURLOPT_URL, $url);
    curl_setopt($ch, CURLOPT_POST, true);
    curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    // Disabling SSL Certificate support temporarly
    curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
    curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($fields));
    // Execute post
    $result = curl_exec($ch);
    if ($result === FALSE) {
        die('Curl failed: ' . curl_error($ch));
    }
    // Close connection
    curl_close($ch);
    return $result;
}