Examine source code of crawell

{
  "manifest_version": 2,
  "name": "Crawell",
  "description": "Crawell – All-in-one web asset extractor & knowledge organizer",
  "version": "0.9.3",
  "icons": {
    "16": "icons/16.png",
    "32": "icons/32.png",
    "48": "icons/48.png",
    "128": "icons/128.png"
  },
  "default_locale": "en",
  "permissions": [
    "storage",
    "tabs",
    "scripting",
    "http://*/*",
    "https://*/*"
  ],
  "web_accessible_resources": [
    "help.html",
    "privacy.html",
    "terms.html",
    "welcome.html"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_title": "Crawell",
    "default_popup": "popup.html"
  },
  "sidebar_action": {
    "default_panel": "sidepanel.html",
    "default_title": "Default Popup Title"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content-scripts/content.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{471d21ca-b99a-4456-8cc2-5bae58d34309}"
    }
  }
}