This is manifest.json for content_scripts

background.html

empty

manifest.json

{
  "manifest_version": 2,

  "name": "test",
  "short_name": "test",
  "description": "test",
  "version": "0.1.0",

  "permissions": [ "activeTab" ],

  "background": {
    "persistent": false,
    "page": "background.html"
  },

  "content_scripts": [
    {
      "matches": [
        "http://vk.com/*",
        "https://vk.com/*"
       ],
      "js": [ "test.js" ]
    }
  ]
}

test.js

(function() {
  console.log('test');
})();