在Chrome扩展程序

Question

我开发了当前页面网址的一个chrome扩展基础。 下面列出了我的chrome扩展文件。

我的manifest.json文件是

{
    "name": "Domain Name",
    "description": "http://stackoverflow.com/questions/14796722/javascript-google-chrome-extension-getting-domain-name",
    "version": "1",
    "manifest_version": 2,
    "content_scripts": [
        {
            "matches": [
                "<all_urls>"
            ],
            "js": [
                "myscript.js"
            ]
        }
    ],
    "browser_action": {
        "default_popup": "popup.html",
"default_icon": {                    
            "38": "icon.png"            
          }
    },
    "background": {
        "scripts": [
            "background.js"
        ]
    },
    "permissions": [
        "tabs",
        "<all_urls>"
    ],
"content_scripts": [
    {
      "matches": ["<all_urls>"],
      "js": ["myscript.js","popup.js"]
    }
  ]
}

我的background.js文件

chrome.tabs.onUpdated.addListener(function (tabId, change, tab) {

    if (tab.url == "https://www.facebook.com/") {
        chrome.browserAction.setIcon({ path: 'BGicon.png' });
    }
    else {
        chrome.browserAction.setIcon({ path: 'icon.png' });
    }
});

myscript.js

console.log(document.domain);

var domainURL = document.domain;

if (document.domain == "facebook.com") {
    alert("Succes");
}

popup.js

document.addEventListener("DOMContentLoaded", function () {
    console.log(document.domain);//It outputs id of extension to console

    renderStatus('Search term: Google image search result: ');

    chrome.tabs.query({ //This method output active URL 
        "active": true,
        "currentWindow": true,
        "status": "complete",
        "windowType": "normal"
    }, function (tabs) {
        for (tab in tabs) {
            console.log(tabs[tab].url);
        }
    });
});


function renderStatus(statusText) {
    document.getElementById('status').textContent = statusText;
}

我想按打开页面设置msg文本。我的意思是如果我打开facebook.com然后弹出消息设置并显示，否则弹出消息不会显示。