Examine source code of Limit - Set Limitda

{
  "manifest_version": 2,
  "name": "Limit - Set Limits for Distracting Sites",
  "short_name": "Limit",
  "description": "Limit your time spent on distracting sites. Limit is an extension that allows you to set time limits for distracting websites.",
  "version": "0.1.4",
  "icons": {
    "16": "images/limit_icon_16.png",
    "19": "images/limit_icon_19.png",
    "32": "images/limit_icon_32.png",
    "38": "images/limit_icon_76.png",
    "48": "images/limit_icon_48.png",
    "128": "images/limit_icon_128.png"
  },
  "browser_action": {
    "default_title": "Limit is enabled.",
    "default_popup": "html/menu.html",
    "default_icon": {
      "16": "images/limit_icon_16.png",
      "19": "images/limit_icon_19.png",
      "32": "images/limit_icon_32.png",
      "38": "images/limit_icon_76.png",
      "48": "images/limit_icon_48.png",
      "128": "images/limit_icon_128.png"
    }
  },
  "background": {
    "scripts": [
      "js/background.js"
    ]
  },
  "web_accessible_resources": [
    "html/*",
    "images/*",
    "fonts/*"
  ],
  "permissions": [
    "tabs",
    "activeTab",
    "storage",
    "idle",
    "notifications"
  ],
  "content_security_policy": "script-src 'self'; object-src 'self'",
  "content_scripts": [
    {
      "matches": [
        "*://*/*"
      ],
      "run_at": "document_start",
      "js": [
        "/js/content_script.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{487ebec5-0def-4bfc-bb37-d75bca408ac6}"
    }
  }
}