相关疑难解决方法(0)

我正在尝试为浏览器的Web扩展测试示例代码.但是,它不起作用.我检查了控制台的谷歌浏览器和Firefox.它不打印任何东西.以下是我的代码:

manifest.json:

{
    "description": "Demonstrating webRequests",
    "manifest_version": 2,
    "name": "webRequest-demo",
    "version": "1.0",

    "permissions": [
        "webRequest"
    ],
    "background": {
        "scripts": ["background.js"]
    }
}

background.js:

function logURL(requestDetails) {
    console.log("Loading: " + requestDetails.url);
}

chrome.webRequest.onBeforeRequest.addListener(
    logURL,
    {urls: ["<all_urls>"]}
);
console.log("Hell o extension background script executed");

我错过了什么吗？