Examine source code of Font Changer

{
  "manifest_version": 2,
  "name": "Font Changer",
  "version": "0.3.4resigned1",
  "description": "Find elements on the page and change their font with just few clicks.",
  "icons": {
    "64": "font-changer/icons/64.png"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "font-changer/content-script/font-changer.js"
      ],
      "css": [
        "font-changer/content-script/font-changer.css"
      ]
    }
  ],
  "browser_action": {
    "default_icon": "font-changer/icons/64.png",
    "default_title": "Font Changer"
  },
  "background": {
    "scripts": [
      "font-changer/background/background.js"
    ]
  },
  "permissions": [
    "activeTab"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{814742d0-4afc-4d25-a210-e25c51da9d6c}"
    }
  }
}