protected function checkBrowserOpera()
    {
        if ($this->checkBrowserUAWithVersion('Opera Mobi', $this->_agent, self::BROWSER_OPERA_MOBILE, true)) {
            return true;
        }

        if ($this->checkSimpleBrowserUA('Opera Mini', $this->_agent, self::BROWSER_OPERA_MINI, true)) {
            return true;
        }

        $version = '';
        $found = $this->checkBrowserUAWithVersion('Opera', $this->_agent, self::BROWSER_OPERA);
        if ($found && $this->getVersion() != self::VERSION_UNKNOWN) {
            $version = $this->getVersion();
        }

        if (!$found || $version == '') {
            if ($this->checkSimpleBrowserUA('Opera', $this->_agent, self::BROWSER_OPERA)) {
                return true;
            }
        }

        if (!$found && $this->checkSimpleBrowserUA('Chrome', $this->_agent, self::BROWSER_CHROME) ) {
            if ($this->checkSimpleBrowserUA('OPR', $this->_agent, self::BROWSER_OPERA)) {
                return true;
            }
        }

        return $found;
    }