Examine source code of facebook_filter

{
  "manifest_version": 2,
  "version": "0.0.1",
  "name": "facebook_blocker",
  "descriptions": "allows you to filter the feeds of facebook",
  "applications": {
    "gecko": {
      "id": "ronnie.jhaa@gmail.com",
      "strict_min_version": "42.0"
    }
  },
  "author": "ronnie j",
  "short_name": "facebook_filter",
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": true
  },
  "options_ui": {
    "page": "options.html"
  },
  "permissions": [
    "storage",
    "https://www.facebook.com/*"
  ],
  "icons": {
    "16": "facebookBlock_16x16.png",
    "48": "facebookBlock_48x48.png",
    "128": "facebookBlock_128x128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "https://www.facebook.com/*"
      ],
      "js": [
        "content.js"
      ]
    }
  ]
}