Facebook.com上的Google Chrome扩展程序Websocket对象错误未定义

Question

我在Google Chrome Extension的contentscript.js文件中使用WebSocket对象时遇到问题。它仅为facebook.com主页生成错误。 Err.Message给了我不确定的价值。我没有得到任何线索，为什么它只在facebook.com上给出错误。在以下行产生错误

var ws = new WebSocket("ws://localhost:3345/");

以下是contentscript.js的代码段：

/////////////////////SendMessage/////////////////////// <br/>
//Description: We are creating websocket(Chrome API).  <br/>
/////////////////////////////////////////////////////// <br/>

function SendMessage(message) {
    try {
        if ("WebSocket" in window) {

            //creating websocket(Chrome API)
            //Below code line produces error on facebook.com
            var ws = new WebSocket("ws://localhost:3345/");

            //Hook function against  ws.onmessage event.
            ws.onmessage = function (evt) {

                OnMessage(evt);
            };

            ws.onopen = function () {
              ws.send( message););
            };

        }
    }
    catch (err) { alert("Err->" + err.Message); }
}

这是mainfest.json代码

{
  "name" : "myextension",
  "version" : "1.1",
  "description" : "me extension detail",
  "background" : {
    "scripts": ["background.js"]
  },

  "content_scripts" : [
    {
      "matches" : [
        "http://*/*",
        "https://*/*"
      ],
      "js" : ["contentscript.js"],
      "run_at" : "document_end",
      "all_frames" : true
    }
  ],
"permissions": [
    "tabs", "<all_urls>",
 "*://*.facebook.com/",
 "*://www.facebook.com/"

  ],

"content_security_policy": "script-src https://www.facebook.com 'self'; object-src 'self'; connect-src https://www.facebook.com",

  "manifest_version": 2
}