v1.4 Dropbox support

library/Dropbox/WebAuthException/Csrf.php

@@ -0,0 +1,21 @@
+<?php
+namespace Dropbox;
+
+/**
+ * Thrown if the given 'state' parameter doesn't contain the CSRF token from the user's session.
+ * This is blocked to prevent CSRF attacks.
+ *
+ * The recommended action is to respond with an HTTP 403 error page.
+ */
+class WebAuthException_Csrf extends \Exception
+{
+    /**
+     * @param string $message
+     *
+     * @internal
+     */
+    function __construct($message)
+    {
+        parent::__construct($message);
+    }
+}