chrome.webRequest.onHeadersReceived.addListener(
    function (details) {
        for (var i in details.responseHeaders)
            if (details.responseHeaders[i].name == "Content-Disposition")
                details.responseHeaders[i].value = "inline; filename=\"\"";
        return {
            responseHeaders: details.responseHeaders
        };
    }, {
        urls: ["http://pcdn.500px.net/*"]
    }, ["blocking", "responseHeaders"]
);