问Background.js找不到注入内容脚本的内容

EN

"content_scripts": [
    {
        "matches": [
            "http://*/*",
            "https://*/*"
        ],
        "css": ["contentstyle.css"],
    "js": ["jquery-1.11.2.min.js", "contentscript.js"],

"background": {
    "persistent": true,
    "scripts": ["background.js"]  
},     

// Add Custom DIV - works OK
var div = document.createElement( 'div' );
div.id = 'infoDiv';
document.body.appendChild( div );
document.getElementById('infoDiv').innerHTML = 'TEST';

// Add menu - gets added, but can't see Injected Content from here
chrome.contextMenus.create({
    "title": "My Right-Click Menu",
    "contexts": ["image"],
    "onclick" : changeDiv
  });

function changeDiv(e)
{
    var divHTML = document.getElementById('infoDiv').innerHTML;
    alert('Current HTML in DIV: ' + divHTML);
}